The ESO Paranal instrumentation program
Author(s):
Luca Pasquini
Show Abstract
The Paranal Instrumentation Programme is responsible for planning and delivering the instruments and the associated infrastructure needed to keep the VLT and La Silla Observatories at the forefront of ground-based astronomy. The VLT second generation instruments KMOS, MUSE and SPHERE have been delivered and are in operations, GRAVITY is under commissioning at the renewed VLTI facility. The Adapative Optics Facility is moving towards completion, as well as the high resolution spectrograph ESPRESSO and the VLTI second generation instrument MATISSE. The mid-IR imager and spectrograph VISIR has been upgraded, and a major upgrade of the CRIRES spectrograph is under way. Finally, two new Multi Object Spectrographs projects have started, one for the VLT (MOONS), one for the 4M VISTA telescope (4MOST), and two new instruments for La Silla, (SOXS and NIRPS) fully funded by the community, are being agreed. The Programme follows a roadmap that foresees one new instrument/project or one upgrade starting every year. Active management, cost to completion and risk policy are in place.
Overview of the instrumentation programme of the 10.4m GTC Telescope
Author(s):
Antonio Cabrera-Lavers;
Romano L. M. Corradi
Show Abstract
We present the instrumentation plan of the 10.4m Gran Telescopio Canarias (GTC) until 2019. It includes a suite of instruments covering a wide wavelength range (from 350 to 2000 nm), with imaging, multiplexed (MOS, IFUs, and Fabry-Perot) spectroscopy at a resolution up to R=30000, polarimetric capabilities, and adaptive optics correction. Up to six instruments will be simultaneously available, taking advantage of five, full-equipped and interchangeable focal configurations of GTC, which include one Main Cassegrain focus, two Nasmyth platforms, and two Folded-Cassegrain foci.
New developments in instrumentation at the W. M. Keck Observatory
Author(s):
Sean M. Adkins;
Ian S. McLean;
Michael P. Fitzgerald;
James E. Larkin;
Hilton A. Lewis;
Christopher Martin;
Dimitri Mawet;
J. X. Prochaska;
Peter Wizinowich
Show Abstract
The W. M. Keck Observatory is committed to maintaining the scientific leadership of our observing community by matching our observers' skills and passions in their fields of astronomical science with a continuing dedication by the Observatory and its collaborators to the development of state of the art instrumentation and systems. Our science driven strategic plan guides these developments and informs our plans for the future. In this paper we describe the performance of recently completed new instruments, instrument upgrades, and infrastructure upgrade projects. We also describe the expected performance of projects currently in the development or construction phases. Projects recently completed include a new laser for the Keck II AO system, the upgrade of the spectrograph detector in the OSIRIS instrument, and the upgrade to the telescope control system on the Keck II telescope. Projects in development include an upgrade to the telescope control system on the Keck I telescope, the blue channel of the Keck Cosmic Web Imager, the red channel of the Keck Cosmic Web Imager, the Keck Planet Finder, a deployable tertiary mirror for the Keck I telescope, an upgrade to the imager of OSIRIS, a major upgrade to the NIRSPEC instrument, and a fiber feed from the Keck II AO system to NIRSPEC.
An overview of current and future instrumentation at the Subaru telescope
Author(s):
Yosuke Minowa;
Naruhisa Takato;
Ikuru Iwata;
Takashi Hattori
Show Abstract
In the past few years, a new prime focus optical imager Hyper Suprime-Cam (HSC), which has 1.5 deg field of view (FoV), is commissioned and started its science operation. Prime-Focus Spectrograph (PFS), which is an optical to near-infrared multiplexed spectrograph over 1.3 deg FoV is currently in the construction phase and will be a next facility instrument to promote the wide-field astronomy at Subaru together with HSC. As a new facility instrument program, ULTIMATE-Subaru, which will develop wide-field near-infrared instruments with the aid of ground-layer adaptive optics system, is being planned. In addition to the new facility instruments, upgrades of the existing facility instruments and developments of several visitor instruments are in progress. This paper gives an overview of current and future instrumentation at the Subaru telescope.
The JCMT future instrumentation project
Author(s):
Jessica T. Dempsey;
Paul T. P. Ho;
Craig Walther;
Per Friberg;
Dan Bintley;
Ming-Tang Chen
Show Abstract
Under the new operational purview of the East Asian Observatory, the JCMT continues to produce premier wide-field submillimetre science. Now the Observatory looks to embark on an ambitious series of instrumentation upgrades and opportunities to keep the telescope at the bleeding edge of its performance capabilities, whilst harnessing the collaborative expertise of the participating EAO regions and its JCMT partners. New heterodyne instruments include a new receiver at 230 GHz, a super array (90 pixels) at 345 GHz and the upgrade possibilities for the continuum camera SCUBA-2. In addition, the opportunities for PI and visiting instruments, including TimePilot and Gismo-2 will be described.
The European Solar Telescope (EST)
Author(s):
Sarah A. Matthews;
Manuel Collados ;
Mihalis Mathioudakis;
Robertus Erdelyi
Show Abstract
The European Solar Telescope (EST) is being designed to optimize studies of the magnetic coupling between the lower layers of the solar atmosphere (the photosphere and chromosphere) in order to investigate the origins and evolution of the solar magnetic field and its role in driving solar activity. In order to achieve this, the thermal, dynamic and magnetic properties of the solar plasma must be probed over many scale heights and at intrinsic scales, requiring the use of multi wavelength spectroscopy and spectropolarimetry at high spatial, spectral and temporal resolution. In this paper we describe some of the over-arching science questions that EST will address and briefly outline the main features of the proposed telescope design and the associated instrumentation package.
FLITECAM: delivery and performance on SOFIA
Author(s):
Sarah E. Logsdon;
Ian S. McLean;
E. E. Becklin;
Ryan T. Hamilton;
William D. Vacca;
Patrick Waddell
Show Abstract
We present a performance report for FLITECAM, a 1-5 μm imager and spectrograph, upon its acceptance and delivery to SOFIA (Stratospheric Observatory for Infrared Astronomy). FLITECAM has two observing configurations: solo configuration and “FLIPO” configuration, which is the co-mounting of FLITECAM with the optical instrument HIPO (PI E. Dunham, Lowell Observatory). FLITECAM was commissioned in the FLIPO configuration in 2014 and flew in the solo configuration for the first time in Fall 2015, shortly after its official delivery to SOFIA. Here we quantify FLITECAM’s imaging and spectral performance in both configurations and discuss the science capabilities of each configuration, with examples from in-flight commissioning and early science data. The solo configuration (which comprises fewer warm optics) has better sensitivity at longer wavelengths. We also discuss the causes of excess background detected in the in-flight FLITECAM images at low elevations and describe the current plan to mitigate the largest contributor to this excess background.
300 nights of science with IGRINS at McDonald Observatory
Author(s):
Gregory Mace;
Hwihyun Kim;
Daniel T. Jaffe;
Chan Park;
Jae-Joon Lee;
Kyle Kaplan;
Young Sam Yu;
In-Soo Yuk;
Moo-Young Chun;
Soojong Pak;
Kang-Min Kim;
Jeong-Eun Lee;
Christopher A. Sneden;
Melike Afsar;
Michael D. Pavel;
Hanshin Lee;
Heeyoung Oh;
Ueejeong Jeong;
Sunkyung Park;
Benjamin Kidder;
Hye-In Lee;
Huynh Anh Nguyen Le;
Jacob McLane;
Michael Gully-Santiago;
Jae Sok Oh;
Sungho Lee;
Narae Hwang;
Byeong-Gon Park
Show Abstract
The Immersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution in the near-infrared. IGRINS employs a silicon immersion grating as the primary disperser, and volume-phase holographic gratings cross-disperse the H and K bands onto Teledyne Hawaii-2RG arrays. The use of an immersion grating facilitates a compact cryostat while providing simultaneous wavelength coverage from 1.45 - 2.5 μm. There are no cryogenic mechanisms in IGRINS and its high-throughput design maximizes sensitivity. IGRINS on the 2.7 meter Harlan J. Smith Telescope at McDonald Observatory is nearly as sensitive as CRIRES at the 8 meter Very Large Telescope. However, IGRINS at R≈45,000 has more than 30 times the spectral grasp of CRIRES* in a single exposure. Here we summarize the performance of IGRINS from the first 300 nights of science since commissioning in summer 2014. IGRINS observers have targeted solar system objects like Pluto and Ceres, comets, nearby young stars, star forming regions like Taurus and Ophiuchus, the interstellar medium, photo dissociation regions, the Galactic Center, planetary nebulae, galaxy cores and super novae. The rich near-infrared spectra of these objects motivate unique science cases, and provide information on instrument performance. There are more than ten submitted IGRINS papers and dozens more in preparation. With IGRINS on a 2.7m telescope we realize signal-to-noise ratios greater than 100 for K=10.3 magnitude sources in one hour of exposure time. Although IGRINS is Cassegrain mounted, instrument flexure is sub-pixel thanks to the compact design. Detector characteristics and stability have been tested regularly, allowing us to adjust the instrument operation and improve science quality. A wide variety of science programs motivate new tools for analyzing high-resolution spectra including multiplexed spectral extraction, atmospheric model fitting, rotation and radial velocity, unique line identification, and circumstellar disk modeling. Here we discuss details of instrument performance, summarize early science results, and show the characteristics of IGRINS as a versatile near-infrared spectrograph and forerunner of future silicon immersion grating spectrographs like iSHELL2 and GMTNIRS.3
VISIR upgrade overview: all's well that ends well
Author(s):
Florian Kerber;
Hans Ulrich Käufl;
Konrad Tristram;
Daniel Asmus;
Pedro Baksai;
Nicola Di Lieto;
Danuta Dobrzycka;
Philippe Duhoux;
Gert Finger;
Christian Hummel;
Derek Ives;
Gerd Jakob;
Lars Lundin;
Dimitri Mawet;
Leander Mehrgan;
Eric Pantin;
Miguel Riquelme;
Joel Sanchez;
Stefan Sandrock;
Ralf Siebenmorgen;
Jörg Stegmeier;
Alain Smette;
Julian Taylor;
Mario van den Ancker;
Guillermo Valdes;
Lars Venema
Show Abstract
We present an overview of the VISIR instrument after its upgrade and return to science operations. VISIR is the midinfrared imager and spectrograph at ESO’s VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan was based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array manufactured by Raytheon. In addition, a new prism spectroscopic mode covers the whole N-band in a single observation. Finally, new scientific capabilities for high resolution and high-contrast imaging are offered by sub-aperture mask and coronagraphic modes. In order to make optimal use of favourable atmospheric conditions, a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012, it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise. It is inherent to the design chosen for this detector and cannot be remedied by changing the detector set-up. Since this is a form of correlated noise, its impact can be limited by modulating the scene recorded by the detector. After careful analysis, we have implemented fast (up to 4 Hz) chopping with field stabilization using the secondary mirror of the VLT. During commissioning, the upgraded VISIR has been confirmed to be more sensitive than the old instrument, and in particular for low-resolution spectroscopy in the N-band, a gain of a factor 6 is realized in observing efficiency. After overcoming several additional technical problems, VISIR is back in Science Operations since April 2015. In addition an upgrade of the IT infrastructure related to VISIR has been conducted in order to support burst-mode operations. Science Verification of the new modes was performed in Feb 2016. The upgraded VISIR is a powerful instrument providing close to background limited performance for diffraction-limited observations at an 8-m telescope. It offers synergies with facilities such as ALMA, JWST, VLTI and SOFIA, while a wealth of targets is available from survey works like WISE. In addition, it will bring confirmation of the technical readiness and scientific value of several aspects for future mid-IR instrumentation at Extremely Large Telescopes. We also present several lessons learned during the project.
Performance updates of HAWK-I and preparation for the commissioning of the system GRAAL+HAWK-I
Author(s):
Pascale Hibon;
Jerome Paufique;
Harald Kuntschner;
Danuta Dobrzycka;
Miska Le Louarn;
Elena Valenti;
Mark Neeser;
Emanuela Pompei;
Robin Arsenault;
Ralf Siebenmorgen;
Pierre-Yves Madec;
Monika Petr-Gotzens;
Carlos La Fuente;
Josefina Urrutia;
Javier Valenzuela;
Roberto Castillo;
Pedro Baksai;
Cesar Enrique Garcia Dabo;
Andreas Jost;
Javier Argomedo;
Johann Kolb;
Mario Kiekebusch;
Norbert Hubin;
Philippe Duhoux;
Ralf Dieter Conzelmann;
Robert Donaldson;
Sebastien Tordo;
Stefan Huber
Show Abstract
The High Acuity Wide field K-band Imager (HAWK-I) instrument is a cryogenic wide field imager operating in the wavelength range 0.9 to 2.5 microns. It has been in operations since 2007 on the UT4 at the Very Large Telescope Observatory in seeing-limited mode. In 2017-2018, GRound Layer Adaptive optics Assisted by Lasers module (GRAAL) will be in operation and the system GRAAL+HAWK-I will be commissioned. It will allow: deeper exposures for nearly point-source objects, or shorter exposure times for reaching the same magnitude, and/or deeper detection limiting magnitude. With GRAAL, HAWK-I will operate more than 80% of the time with an equivalent K-band seeing of 0.55" (instead of 0.7" without GRAAL). GRAAL is already installed and the operations without adaptive optics were commissioned in 2015. We discuss here the latest updates on performance from HAWK-I without Adaptive Optics (AO) and the preparation for the commissioning of the system GRAAL+HAWK-I.
Making SPIFFI SPIFFIER: upgrade of the SPIFFI instrument for use in ERIS and performance analysis from re-commissioning
Author(s):
E. M. George;
D. Gräff;
H. Feuchtgruber;
M. Hartl;
F. Eisenhauer;
A. Buron;
R. Davies;
R. Genzel;
H. Huber;
C. Rau;
M. Plattner;
E. Wiezorrek;
H. Weisz;
P. Amico;
A. Glindemann;
G. Hau;
H. Kuntschner
Show Abstract
SPIFFI is an AO-fed integral field spectrograph operating as part of SINFONI on the VLT, which will be upgraded and reused as SPIFFIER in the new VLT instrument ERIS. In January 2016, we used new technology developments to perform an early upgrade to optical subsystems in the SPIFFI instrument so ongoing scientific programs can make use of enhanced performance before ERIS arrives in 2020. We report on the upgraded components and the performance of SPIFFI after the upgrade, including gains in throughput and spatial and spectral resolution. We show results from re-commissioning, highlighting the potential for scientific programs to use the capabilities of the upgraded SPIFFI. Finally, we discuss the additional upgrades for SPIFFIER which will be implemented before it is integrated into ERIS.
The "+" for CRIRES: enabling better science at infrared wavelength and high spectral resolution at the ESO VLT
Author(s):
Reinhold J. Dorn;
Roman Follert;
Paul Bristow;
Claudio Cumani;
Siegfried Eschbaumer;
Jason Grunhut;
Andreas Haimerl;
Artie Hatzes;
Ulrike Heiter;
Renate Hinterschuster;
Derek J. Ives;
Yves Jung;
Florian Kerber;
Barbara Klein;
Alexis Lavail;
Jean Louis Lizon;
Tom Löwinger;
Ignacio Molina-Conde;
Belinda Nicholson;
Thomas Marquart;
Ernesto Oliva;
Livia Origlia;
Luca Pasquini;
Jérôme Paufique;
Nikolai Piskunov;
Ansgar Reiners;
Ulf Seemann;
Jörg Stegmeier;
Eric Stempels;
Sebastien Tordo
Show Abstract
The adaptive optics (AO) assisted CRIRES instrument is an IR (0.92 - 5.2 μm) high-resolution spectrograph was in operation from 2006 to 2014 at the Very Large Telescope (VLT) observatory. CRIRES was a unique instrument, accessing a parameter space (wavelength range and spectral resolution) up to now largely uncharted. It consisted of a single-order spectrograph providing long-slit (40 arcsecond) spectroscopy with a resolving power up to R=100 000. However the setup was limited to a narrow, single-shot, spectral range of about 1/70 of the central wavelength, resulting in low observing efficiency for many scientific programmes requiring a broad spectral coverage. The CRIRES upgrade project, CRIRES+, transforms this VLT instrument into a cross-dispersed spectrograph to increase the simultaneously covered wavelength range by a factor of ten. A new and larger detector focal plane array of three Hawaii 2RG detectors with 5.3 μm cut-off wavelength will replace the existing detectors. For advanced wavelength calibration, custom-made absorption gas cells and an etalon system will be added. A spectro-polarimetric unit will allow the recording of circular and linear polarized spectra. This upgrade will be supported by dedicated data reduction software allowing the community to take full advantage of the new capabilities offered by CRIRES+. CRIRES+ has now entered its assembly and integration phase and will return with all new capabilities by the beginning of 2018 to the Very Large Telescope in Chile. This article will provide the reader with an update of the current status of the instrument as well as the remaining steps until final installation at the Paranal Observatory.
AOLI: near-diffraction limited imaging in the visible on large ground-based telescopes
Author(s):
Craig Mackay;
Rafael Rebolo;
David L. King;
Lucas Labadie;
Marta Puga;
Antonio Pérez Garrido;
Carlos Colodro-Conde;
Roberto L. Lopez;
Balaji Muthusubramanian;
Alejandro Oscoz;
J. Rodríguez Ramos;
Luis F. Rodrigo-Ramos;
J. J. Fernandez-Valdivia;
Sergio Velasco
Show Abstract
The combination of Lucky Imaging with a low order adaptive optics system was demonstrated very successfully on the Palomar 5m telescope nearly 10 years ago. It is still the only system to give such high-resolution images in the visible or near infrared on ground-based telescope of faint astronomical targets. The development of AOLI for deployment initially on the WHT 4.2 m telescope in La Palma, Canary Islands, will be described in this paper. In particular, we will look at the design and status of our low order curvature wavefront sensor which has been somewhat simplified to make it more efficient, ensuring coverage over much of the sky with natural guide stars as reference object. AOLI uses optically butted electron multiplying CCDs to give an imaging array of 2000 x 2000 pixels.
LINC-NIRVANA at LBT: final preparations for first light
Author(s):
T. M. Herbst;
R. Ragazzoni;
T. Bertram;
P. Bizenberger;
F. Briegel;
R. Hofferbert;
M. Kürster
Show Abstract
LINC-NIRVANA is an innovative, high-resolution near-infrared imager for the Large Binocular Telescope. Its Multi- Conjugate Adaptive Optics system uses natural guide-stars and provides high sky coverage for single-eye, binocular, and eventually, interferometric observations. We report on final lab integration and system level testing, as well as technical and logistical challenges of shipping and installing a large, delicate, complex instrument. LINC-NIRVANA is currently at LBT undergoing final alignment and tests before First Light late this fall. Managing the transition to operations involves the interactions between telescope alignment and calibration, commissioning of the instrument, and executing the Early Science plan.
Laboratory testing and performance verification of the CHARIS integral field spectrograph
Author(s):
Tyler D. Groff;
Jeffrey Chilcote;
N. Jeremy Kasdin;
Michael Galvin;
Craig Loomis;
Michael A. Carr;
Timothy Brandt;
Gillian Knapp;
Mary Anne Limbach;
Olivier Guyon;
Nemanja Jovanovic;
Michael W. McElwain;
Naruhisa Takato;
Masahiko Hayashi
Show Abstract
The Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) is an integral field spectrograph (IFS) that has been built for the Subaru telescope. CHARIS has two imaging modes; the high-resolution mode is R82, R69, and R82 in J, H, and K bands respectively while the low-resolution discovery mode uses a second low-resolution prism with R19 spanning 1.15-2.37 microns (J+H+K bands). The discovery mode is meant to augment the low inner working angle of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) adaptive optics system, which feeds CHARIS a coronagraphic image. The goal is to detect and characterize brown dwarfs and hot Jovian planets down to contrasts five orders of magnitude dimmer than their parent star at an inner working angle as low as 80 milliarcseconds. CHARIS constrains spectral crosstalk through several key aspects of the optical design. Additionally, the repeatability of alignment of certain optical components is critical to the calibrations required for the data pipeline. Specifically, the relative alignment of the lenslet array, prism, and detector must be highly stable and repeatable between imaging modes. We report on the measured repeatability and stability of these mechanisms, measurements of spectral crosstalk in the instrument, and the propagation of these errors through the data pipeline. Another key design feature of CHARIS is the prism, which pairs Barium Fluoride with Ohara L-BBH2 high index glass. The dispersion of the prism is significantly more uniform than other glass choices, and the CHARIS prisms represent the first NIR astronomical instrument that uses L-BBH2 as the high index material. This material choice was key to the utility of the discovery mode, so significant efforts were put into cryogenic characterization of the material. The final performance of the prism assemblies in their operating environment is described in detail. The spectrograph is going through final alignment, cryogenic cycling, and is being delivered to the Subaru telescope in April 2016. This paper is a report on the laboratory performance of the spectrograph, and its current status in the commissioning process so that observers will better understand the instrument capabilities. We will also discuss the lessons learned during the testing process and their impact on future high-contrast imaging spectrographs for wavefront control.
Opening a new window on the southern stars for less money: PAIX the first Antarctica polar mission photometer
Author(s):
Merieme Chadid;
Jean Vernin;
Lyu Abe;
Karim Agabi;
George Jumper;
George W. Preston;
Chris Sneden;
Liyong Liu;
Yongqiang Yao;
H.-S Wang;
Éric Aristidi;
J.-P. Rivet;
Marcel Carbillet;
Ch. Giordano;
E. Bondoux;
L. Moggio;
H. Trinquet
Show Abstract
In this invited paper, we implement a new way to study the stellar oscillations, pulsations and their evolutionary properties with long uninterrupted and continuous precision observations over 150 days from the ground, and without the regular interruptions imposed by the earth rotation. PAIX–First Robotic Antarctica Polar Mission– gives a new insight to cope with unresolved stellar enigma and stellar oscillation challenges and offers a great opportunity to benefit from an access to the best astronomical site on Earth –DomeC–. The project is made of low cost commercial components, and achieves astrophysical measurement time-series of stellar physics fields, challenging photometry from space that shows large gaps in terms of flexibility during the observing runs, the choice of targets, the repair of failures and the inexorable high costs. PAIX has yet more advantages than space missions in observing in UBV RI bands and then collecting unprecedented simultaneous multicolor light curves of several targets. We give a brief history of the Astronomy in Antarctica and describe the first polar robotized mission PAIX and the outcome of stellar physics from the heart of Antarctica during several polar nights. We briefly discuss our first results and perspectives on the pulsating stars and its evolution from Antarctica, especially the connection between temporal hydrodynamic phenomena and cyclic modulations. Finally, we highlight the impact of PAIX on the stellar physics study and the remaining challenges to successfully accomplish the Universe explorations under extreme conditions.
Six winters of photometry from Dome C, Antarctica: challenges, improvements, and results from the ASTEP experiment
Author(s):
N. Crouzet;
D. Mékarnia;
T. Guillot;
L. Abe;
A. Agabi;
J.-P. Rivet;
I. Gonçalves;
F.-X. Schmider;
J.-B. Daban;
Y. Fanteï-Caujolle;
C. Gouvret;
D. D. R. Bayliss;
G. Zhou;
E. Aristidi;
T. Fruth;
A. Erikson;
H. Rauer;
J. Szulágyi;
E. Bondoux;
Z. Challita;
C. Pouzenc;
F. Fressin;
F. Valbousquet;
M. Barbieri;
A. Blazit;
S. Bonhomme;
F. Bouchy;
J. Gerakis;
G. Bouchez
Show Abstract
ASTEP (Antarctica Search for Transiting ExoPlanets) is a pilot project that aims at searching and characterizing transiting exoplanets from Dome C in Antarctica and to qualify this site for photometry in the visible. Two instruments were installed at Dome C and ran for six winters in total. The analysis of the collected data is nearly complete. We present the operation of the instruments, and the technical challenges, limitations, and possible solutions in light of the data quality. The instruments performed continuous observations during the winters. Human interventions are required mainly for regular inspection and ice dust removal. A defrosting system is efficient at preventing and removing ice on the mirrors. The PSF FWHM is 4.5 arcsec on average which is 2.5 times larger than the specification, and is highly variable; the causes are the poor ground-level seeing, the turbulent plumes generated by the heating system, and to a lower extent the imperfect optical alignment and focusing, and some astigmatism. We propose solutions for each of these aspects that would largely increase the PSF stability. The astrometric and guiding precisions are satisfactory and would deserve only minor improvements. Major issues are encountered with the camera shutter which did not close properly after two winters; we minimized this issue by heating the shutter and by developing specific image calibration algorithms. Finally, we summarize the site testing and science results obtained with ASTEP. Overall, the ASTEP experiment will serve as a basis to design and operate future optical and near-infrared telescopes in Antarctica.
GLUV: a balloon-borne high-cadence ultraviolet monitoring telescope for supernova shock breakouts and exoplanet atmospheres
Author(s):
Rob Sharp;
B. Tucker;
R. Ridden-Harper;
G. Bloxham;
M. Petkovic
Show Abstract
Routine photometric monitoring at near-ultraviolet wavelengths (< 400 nm) is compromised from the ground due to highly variable atmospheric transmission and cloud cover. The GLUV project will mount a modest sized telescope (200 mm primary) on a series of long-duration high-altitude balloon flights. The wide field camera (~7 deg2) will perform high cadence (10-300 second rolling integrations) each night for campaign durations of three to six months. The principle science mission is the early-time detection of supernova shock-breakout at near-ultraviolet wavelengths. Additionally, early design analysis has shown the system is also able to probe the atmospheric composition of exoplanet atmospheres through the combination of UV transit measurements with ground-based measurements at longer wavelengths. In this presentation we consider the specifications for a long-duration balloon platform for such a mission, focusing on the necessary mission requirements (sensitivity, sky coverage, cadence etc.) and the available platform suitability. Particular attention is paid to platform flight altitude and atmospheric transmission.
Evryscope Robotilter automated camera / ccd alignment system
Author(s):
Jeff K. Ratzloff;
Nicholas M. Law;
Octavi Fors;
Daniel del Ser;
Henry T. Corbett
Show Abstract
We have deployed a new class of telescope, the Evryscope, which opens a new parameter space in optical astronomy - the ability to detect short time scale events across the entire sky simultaneously. The system is a gigapixel-scale array camera with an 8000 sq. deg. field of view, 13 arcsec per pixel sampling, and the ability to detect objects brighter than g = 16 in each 2-minute exposure. The Evryscope is designed to find transiting exoplanets around exotic stars, as well as detect nearby supernovae and provide continuous records of distant relativistic explosions like gamma-ray-bursts. The Evryscope uses commercially available CCDs and optics; the machine and assembly tolerances inherent in the mass production of these parts introduce problematic variations in the lens / CCD alignment which degrades image quality. We have built an automated alignment system (Robotilters) to solve this challenge. In this paper we describe the Robotilter system, mechanical and software design, image quality improvement, and current status.
HiPERCAM: a high-speed quintuple-beam CCD camera for the study of rapid variability in the universe
Author(s):
Vikram S. Dhillon;
Thomas R. Marsh;
Naidu Bezawada;
Martin Black;
Simon Dixon;
Trevor Gamble;
David Henry;
Paul Kerry;
Stuart Littlefair;
David W. Lunney;
Timothy Morris;
James Osborn;
Richard W. Wilson
Show Abstract
HiPERCAM is a high-speed camera for the study of rapid variability in the Universe. The project is funded by a Ɛ3.5M European Research Council Advanced Grant. HiPERCAM builds on the success of our previous instrument, ULTRACAM, with very significant improvements in performance thanks to the use of the latest technologies. HiPERCAM will use 4 dichroic beamsplitters to image simultaneously in 5 optical channels covering the u’g’r’I’z’ bands. Frame rates of over 1000 per second will be achievable using an ESO CCD controller (NGC), with every frame GPS timestamped. The detectors are custom-made, frame-transfer CCDs from e2v, with 4 low noise (2.5e-) outputs, mounted in small thermoelectrically-cooled heads operated at 180 K, resulting in virtually no dark current. The two reddest CCDs will be deep-depletion devices with anti-etaloning, providing high quantum efficiencies across the red part of the spectrum with no fringing. The instrument will also incorporate scintillation noise correction via the conjugate-plane photometry technique. The opto-mechanical chassis will make use of additive manufacturing techniques in metal to make a light-weight, rigid and temperature-invariant structure. First light is expected on the 4.2m William Herschel Telescope on La Palma in 2017 (on which the field of view will be 10' with a 0.3"/pixel scale), with subsequent use planned on the 10.4m Gran Telescopio Canarias on La Palma (on which the field of view will be 4' with a 0.11"/pixel scale) and the 3.5m New Technology Telescope in Chile.
The PAU camera at the WHT
Author(s):
Cristóbal Padilla;
Otger Ballester;
Laia Cardiel-Sas;
Jorge Carretero;
Ricard Casas;
Javier Castilla;
Martin Croce;
Manuel Delfino;
Martin Eriksen;
Enrique Fernández;
Pablo Fosalba;
Juan García-Bellido;
Enrique Gaztañaga;
Ferràn Grañena;
Cales Hernández;
Jorge Jiménez ;
Luis Lopez;
Pol Martí;
Ramon Miquel;
Christian Niessner;
Cristóbal Pío;
Rafael Ponce;
Eusebio Sánchez ;
Santiago Serrano;
Ignacio Sevilla;
Nadia Tonello;
Juan de Vicente
Show Abstract
The PAU (Physics of the Accelerating Universe) project goal is the study of dark energy with a new photometric technique aiming at obtaining photo-z resolution for Luminous Red Galaxies (LRGs) roughly one order of magnitude better than current photometric surveys. To accomplish this, a new large field of view camera (PAUCam) has been built and commissioned at the William Herschel Telescope (WHT). With the current WHT corrector, the camera covers ~1 degree diameter Field of View (FoV). The focal plane consists of 18 2kx4k Hamamatsu fully depleted CCDs, with high quantum efficiency up to 1 μm. To maximize the detector coverage within the FoV, filters are placed in front of the CCD's inside the camera cryostat (made of carbon fiber material) using a challenging movable tray system. The camera uses a set of 40 narrow band filters ranging from ~4400 to ~8600 angstroms complemented with six standard broad-band filters, ugrizY. Here, we describe the camera and its first commissioning results. The PAU project aims to cover roughly 100 square degrees and to obtain accurate photometric redshifts for galaxies down to iAB ~ 22:5 detecting also galaxies down to iAB ~ 24 with less precision in redshift. With this data set we will obtain competitive constraints in cosmological parameters using both weak lensing and galaxy clustering as main observational probes.
A near-infrared SETI experiment: commissioning, data analysis, and performance results
Author(s):
Jérôme Maire;
Shelley A. Wright;
Patrick Dorval;
Frank D. Drake;
Andres Duenas;
Howard Isaacson;
Geoffrey W. Marcy;
Andrew Siemion;
Remington P. S. Stone;
Melisa Tallis;
Richard R. Treffers;
Dan Werthimer
Show Abstract
Over the last two decades, Optical Search for Extra-Terrestrial Intelligence experiments have been conducted to search for either continuous or pulsed visible-light laser beacons that could be used for interstellar communication or energy transmission. Near-infrared offers a compelling window for signal transmission since there is a decrease in interstellar extinction and Galactic background compared to optical wavelengths. An innovative Near-InfraRed and Optical SETI (NIROSETI) instrument has been designed and constructed to take advantage of a new generation of fast (> 1 Ghz) low-noise near-infrared avalanche photodiodes to search for nanosecond pulsed near-infrared (850 - 1650 nm) pulses. The instrument was successfully installed and commissioned at the Nickel (1m) telescope at Lick Observatory in March 2015. We will describe the overall design of the instrument with a focus on methods developed for data acquisition and reduction for near-infrared SETI. Time and height analyses of the pulses produced by the detectors are performed to search for periodicity and coincidences in the signals. We will further discuss our NIROSETI survey plans.
Performance of the e2v 1.2 GPix cryogenic camera for the J-PAS 2.5m survey telescope
Author(s):
M. S. Robbins;
M. Bastable;
A. Bates;
M. Dryer;
S. Eames;
G. Fenemore-Jones;
G. Haddow;
P. R. Jorden;
B. Lane;
A. Marin-Franch;
J. Mortimer;
I. Palmer;
N. Puttay;
R. Renshaw;
M. Smith;
K. Taylor;
J. Tearle;
P. Weston;
P. Wheeler;
J. Worley
Show Abstract
The J-PAS project will perform a five-year survey of the northern sky from a new 2.5m telescope in Teruel, Spain. In this paper the build and factory testing of the commercially supplied cryogenic camera is described. The 1.2 Giga-pixel focal plane is contained within a novel liquid-nitrogen cooled vacuum cryostat, which maintains the flatness for the cooled, 0.45m diameter focal plane to better than 27 μm peak to valley. The cooling system controls the focal plane to a temperature of -100°C with a variation across the focal plane of better than 2.5oC and a stability of better than +/- 0.5 °C over the long periods of operation required. The proximity drive electronics achieves total system level noise performance better than 5 e- from the 224-channel CCD system.
CARMENES: an overview six months after first light
Author(s):
A. Quirrenbach;
P. J. Amado;
J. A. Caballero;
R. Mundt;
A. Reiners;
I. Ribas;
W. Seifert;
M. Abril;
J. Aceituno;
F. J. Alonso-Floriano;
H. Anwand-Heerwart;
M. Azzaro;
F. Bauer;
D. Barrado;
S. Becerril;
V. J. S. Bejar;
D. Benitez;
Z. M. Berdinas;
M. Brinkmöller;
M. C. Cardenas;
E. Casal;
A. Claret;
J. Colomé;
M. Cortes-Contreras;
S. Czesla;
M. Doellinger;
S. Dreizler;
C. Feiz;
M. Fernandez;
I. M. Ferro;
B. Fuhrmeister;
D. Galadi;
I. Gallardo;
M. C. Gálvez-Ortiz;
A. Garcia-Piquer;
R. Garrido;
L. Gesa;
V. Gómez Galera;
J. I. González Hernández;
R. Gonzalez Peinado;
U. Grözinger;
J. Guàrdia;
E. W. Guenther;
E. de Guindos;
H.-J. Hagen;
A. P. Hatzes;
P. H. Hauschildt;
J. Helmling;
T. Henning;
D. Hermann;
R. Hernández Arabi;
L. Hernández Castaño;
F. Hernández Hernando;
E. Herrero;
A. Huber;
K. F. Huber;
P. Huke;
S. V. Jeffers;
E. de Juan;
A. Kaminski;
M. Kehr;
M. Kim;
R. Klein;
J. Klüter;
M. Kürster;
M. Lafarga;
L. M. Lara;
A. Lamert;
W. Laun;
R. Launhardt;
U. Lemke;
R. Lenzen;
M. Llamas;
M. Lopez del Fresno;
M. López-Puertas;
J. López-Santiago;
J. F. Lopez Salas;
H. Magan Madinabeitia;
U. Mall;
H. Mandel;
L. Mancini;
J. A. Marin Molina;
D. Maroto Fernández;
E. L. Martín;
S. Martín-Ruiz;
C. Marvin;
R. J. Mathar;
E. Mirabet;
D. Montes;
J. C. Morales;
R. Morales Muñoz;
E. Nagel;
V. Naranjo;
G. Nowak;
E. Palle;
J. Panduro;
V. M. Passegger;
A. Pavlov;
S. Pedraz;
E. Perez;
D. Pérez-Medialdea;
M. Perger;
M. Pluto;
A. Ramón ;
R. Rebolo;
P. Redondo;
S. Reffert;
S. Reinhart;
P. Rhode;
H.-W. Rix;
F. Rodler;
E. Rodríguez;
C. Rodríguez López;
R. R. Rohloff;
A. Rosich;
M A. Sanchez Carrasco;
J. Sanz-Forcada;
P. Sarkis;
L. F. Sarmiento;
S. Schäfer;
J. Schiller;
C. Schmidt;
J. H. M. M. Schmitt;
P. Schöfer;
A. Schweitzer;
D. Shulyak;
E. Solano;
O. Stahl;
C. Storz;
H. M. Tabernero;
M. Tala;
L. Tal-Or;
R.-G. Ulbrich;
G. Veredas;
J. I. Vico Linares;
F. Vilardell;
K. Wagner;
J. Winkler;
M.-R. Zapatero Osorio;
M. Zechmeister;
M. Ammler-von Eiff;
G. Anglada-Escudé;
C. del Burgo;
M. L. Garcia-Vargas;
A. Klutsch;
J.-L. Lizon;
M. Lopez-Morales;
A. Ofir;
A. Pérez-Calpena;
M. A. C. Perryman;
E. Sánchez-Blanco ;
J. B. P. Strachan;
J. Stürmer;
J. C. Suárez;
T. Trifonov;
S. M. Tulloch;
W. Xu
Show Abstract
The CARMENES instrument is a pair of high-resolution (R⪆80,000) spectrographs covering the wavelength range from 0.52 to 1.71 μm, optimized for precise radial velocity measurements. It was installed and commissioned at the 3.5m telescope of the Calar Alto observatory in Southern Spain in 2015. The first large science program of CARMENES is a survey of ~ 300 M dwarfs, which started on Jan 1, 2016. We present an overview of all subsystems of CARMENES (front end, fiber system, visible-light spectrograph, near-infrared spectrograph, calibration units, etalons, facility control, interlock system, instrument control system, data reduction pipeline, data flow, and archive), and give an overview of the assembly, integration, verification, and commissioning phases of the project. We show initial results and discuss further plans for the scientific use of CARMENES.
WISDOM: the WIYN spectrograph for Doppler monitoring: a NASA-NSF concept for an extreme precision radial velocity instrument in support of TESS
Author(s):
Gábor Fűrész;
Robert Simcoe;
Stuart I. Barnes;
Lars A. Buchhave;
Mark Egan;
Rick Foster;
Tim Hellickson;
Andrew Malonis;
David Phillips;
Stephen Shectman;
Ronald Walsworth;
Josh Winn;
Deborah Woods
Show Abstract
The Kepler mission highlighted that precision radial velocity (PRV) follow-up is a real bottleneck in supporting transiting exoplanet surveys. The limited availability of PRV instruments, and the desire to break the “1 m/s” precision barrier, prompted the formation of a NASA-NSF collaboration ‘NN-EXPLORE’ to call for proposals designing a new Extreme Precision Doppler Spectrograph (EPDS). By securing a significant fraction of telescope time on the 3.5m WIYN at Kitt Peak, and aiming for unprecedented long-term precision, the EPDS instrument will provide a unique tool for U.S. astronomers in characterizing exoplanet candidates identified by TESS. One of the two funded instrument concept studies is led by the Massachusetts Institute of Technology, in consortium with Lincoln Laboratories, Harvard-Smithsonian Center for Astrophysics and the Carnegie Observatories. This paper describes the instrument concept WISDOM (WIYN Spectrograph for DOppler Monitoring) prepared by this team. WISDOM is a fiber fed, environmentally controlled, high resolution (R=110k), asymmetric white-pupil echelle spectrograph, covering a wide 380-1300nm wavelength region. Its R4 and R6 echelle gratings provide the main dispersion, symmetrically mounted on either side of a vertically aligned, vacuum-enclosed carbon fiber optical bench. Each grating feeds two cameras and thus the resulting wavelength range per camera is narrow enough that the VPHG cross-dispersers and employed anti-reflection coatings are highly efficient. The instrument operates near room temperature, and so thermal background for the near-infrared arm is mitigated by thermal blocking filters and a short (1.7μm) cutoff HgCdTe detector. To achieve high resolution while maintaining small overall instrument size (100/125mm beam diameter), imposed by the limited available space within the observatory building, we chose to slice the telescope pupil 6 ways before coupling light into fibers. An atmospheric dispersion corrector and fast tip-tilt system assures maximal light gathering within the 1.2″ entrance aperture. The six octagonal fibers corresponding to each slice of the pupil employ ball-lens double scramblers to stabilize the near- and far-fields. Three apiece are coupled into each of two rectangular fibers, to mitigate modal nose and present a rectilinear illumination pattern at the spectrograph's slit plane. Wavelength solutions are derived from ThAr lamps and an extremely wide coverage dual-channel laser frequency comb. Data is reduced on the fly for evaluation by a custom pipeline, while daily archives and extended scope data reduction products are stored on NExScI servers, also managing archives and access privileges for GTO and GO programs. Note: individual papers, submitted along this main paper, describe the details of subsystems such as the optical design (Barnes et al., 9908-247), the fiber link design (Fűrész et al., 9908-281), and the pupil slicer (Egan et al., 9912-183).
The Gemini High-Resolution Optical SpecTrograph (GHOST)
Author(s):
Andrew I. Sheinis;
Andre Anthony;
Gabriella Baker;
Gregory S. Burley;
Vladimir Churilov;
Michael Edgar;
Michael Ireland;
Yuriy Kondrat;
John Pazder;
Gordon Robertson;
Peter J. Young;
Ross Zhelem
Show Abstract
The Gemini High-Resolution Optical SpecTrograph (GHOST) is the newest instrument chosen for the Gemini South telescope. It is being developed by a collaboration between the Australian Astronomical Observatory (AAO), the NRC - Herzberg in Canada and the Australian National University (ANU). Using recent technological advances and several novel concepts it will deliver spectroscopy with R>50,000 for up to 2 objects simultaneously or R>75,000 for a single object. GHOST uses a fiber-image-slicer to allow use of a much smaller spectrograph than that nominally required by the resolution-slit–width product. With its fiber feed, we expect GHOST to have a sensitivity in the wavelength range between 363-950 nm that equals or exceeds that of similar directly-fed instruments on world-class facilities. GHOST has entered the build phase. We report the status of the instrument and describe the technical advances and the novel aspects, such as the lenslet-based slit reformatting. Finally, we describe the unique scientific role this instrument will have in an international context, from exoplanets through stellar elemental abundances to the distant Universe. Keywords: Gemini, spectrograph, spectroscopy, ́echelle, high resolution, radial velocity, fiber image slicer, integral field unit.
Development and construction of MAROON-X
Author(s):
Andreas Seifahrt;
Jacob L. Bean;
Julian Stürmer;
Luke Gers;
Deon S. Grobler;
Tony Reed;
Damien J. Jones
Show Abstract
We report on the development and construction of a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. MAROON-X will be optimized to find and characterize rocky planets around nearby M dwarfs with an intrinsic per measurement noise floor below 1ms-1. The instrument is based on a commercial echelle spectrograph customized for high stability and throughput. A microlens array based pupil slicer and double scrambler, as well as a rubidium-referenced etalon comb calibrator will turn this spectrograph into a high-precision radial-velocity machine. MAROON-X will undergo extensive lab tests in the second half of 2016.
iLocater: a diffraction-limited Doppler spectrometer for the Large Binocular Telescope
Author(s):
Justin R. Crepp;
Jonathan Crass;
David King;
Andrew Bechter;
Eric Bechter;
Ryan Ketterer;
Robert Reynolds;
Philip Hinz;
Derek Kopon;
David Cavalieri;
Louis Fantano;
Corina Koca;
Eleanya Onuma;
Karl Stapelfeldt;
Joseph Thomes;
Sheila Wall;
Steven Macenka;
James McGuire;
Ronald Korniski;
Leonard Zugby;
Joshua Eisner;
B Scott Gaudi;
Fred Hearty;
Kaitlin Kratter;
Marc Kuchner;
Giusi Micela;
Matthew Nelson;
Isabella Pagano;
Andreas Quirrenbach;
Christian Schwab;
Michael Skrutskie;
Alessandro Sozzetti;
Charles Woodward;
Bo Zhao
Show Abstract
We are developing a stable and precise spectrograph for the Large Binocular Telescope (LBT) named “iLocater.” The instrument comprises three principal components: a cross-dispersed echelle spectrograph that operates in the YJ-bands (0.97-1.30 μm), a fiber-injection acquisition camera system, and a wavelength calibration unit. iLocater will deliver high spectral resolution (R~150,000-240,000) measurements that permit novel studies of stellar and substellar objects in the solar neighborhood including extrasolar planets. Unlike previous planet-finding instruments, which are seeing-limited, iLocater operates at the diffraction limit and uses single mode fibers to eliminate the effects of modal noise entirely. By receiving starlight from two 8.4m diameter telescopes that each use “extreme” adaptive optics (AO), iLocater shows promise to overcome the limitations that prevent existing instruments from generating sub-meter-per-second radial velocity (RV) precision. Although optimized for the characterization of low-mass planets using the Doppler technique, iLocater will also advance areas of research that involve crowded fields, line-blanketing, and weak absorption lines.
GIARPS: the unique VIS-NIR high precision radial velocity facility in this world
Author(s):
R. Claudi;
S. Benatti;
I. Carleo;
A. Ghedina;
E. Molinari;
E. Oliva;
A. Tozzi;
A. Baruffolo;
M. Cecconi;
R. Cosentino;
D. Fantinel;
L. Fini;
F. Ghinassi;
M. Gonzalez;
R. Gratton;
J. Guerra Sr.;
A. Harutyunyan;
N. Hernandez;
M. Iuzzolino;
M. Lodi;
L. Malavolta;
J. Maldonado;
G. Micela;
N. Sanna;
J. Sanjuan;
S. Scuderi;
A. Sozzetti;
H. Pérez Ventura;
H. Diaz Marcos;
A. Galli;
C. Gonzalez;
L. Riverol;
C. Riverol
Show Abstract
GIARPS (GIAno and haRPS) is a project devoted to have on the same focal station of the Telescopio Nazionale Galileo (TNG) both the high resolution spectrographs HARPS-N (VIS) and GIANO (NIR) working simultaneously. This could be considered the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at a high resolution (R=115,000 in the visual and R=50,000 in the IR) and over in a wide spectral range (0.383 - 2.45 μm) in a single exposure. The science case is very broad, given the versatility of such an instrument and the large wavelength range. A number of outstanding science cases encompassing mainly extra-solar planet science starting from rocky planet search and hot Jupiters, atmosphere characterization can be considered. Furthermore both instrument can measure high precision radial velocity by means the simultaneous thorium technique (HARPS - N) and absorbing cell technique (GIANO) in a single exposure. Other science cases are also possible. Young stars and proto- planetary disks, cool stars and stellar populations, moving minor bodies in the solar system, bursting young stellar objects, cataclysmic variables and X-ray binary transients in our Galaxy, supernovae up to gamma-ray bursts in the very distant and young Universe, can take advantage of the unicity of this facility both in terms of contemporaneous wide wavelength range and high resolution spectroscopy.
Precision radial velocities with inexpensive compact spectrographs
Author(s):
Christopher H. Betters;
Alex Murray;
Joss Bland-Hawthorn;
Sergio G. Leon-Saval
Show Abstract
High-precision astronomical spectrographs routinely employed to detect planets via the radial velocity method are generally large and expensive instruments. We present our progress developing a compact spectrograph using commercial ‘off-the-shelf’ components that can achieve similar precision at a fraction of the cost. The spectrograph, PIMMS Visible, has a resolving power of R-50,000 operating in the visible regime. We are able to obtain RMS velocity precisions of better than ~1 m/s by calibrating with a stabilised single-mode etalon. As a technology proof we attempt to detect the solar 5- minute period p-mode oscillations (a few m/s signal).
First light results from the HERMES spectrograph at the AAT
Author(s):
Andrew I. Sheinis
Show Abstract
The High Efficiency and Resolution Multi Element Spectrograph, HERMES is a facility-class optical spectrograph for the AAT. It is designed primarily for Galactic Archeology, the first major attempt to create a detailed understanding of galaxy formation and evolution by studying the history of our own galaxy, the Milky Way. The goal of the Galactic Archeology with Hermes (GALAH) survey is to reconstruct the mass assembly history of the Milky Way, through a detailed spatially tagged abundance study of one million stars. The spectrograph is based at the Anglo Australian Telescope (AAT) and is fed by the existing 2dF robotic fiber positioning system. The spectrograph uses VPH-gratings to achieve a spectral resolving power of 28,000 in standard mode and also provides a high-resolution mode ranging between 40,000 to 50,000 using a slit mask. The GALAH survey requires a SNR greater than 100 for a star brightness of V=14. The total spectral coverage of the four channels is about 100nm between 370 and 1000nm for up to 392 simultaneous targets within the 2- degree field of view. Hermes was commissioned in late 2013, with the GALAH Pilot starting in parallel with the commissioning. The GALAH survey started in early 2014 is currently about 33% complete. We present a description of the motivating science; an overview the instrument; and a status report on GALAH Survey.
Hector: a new massively multiplexed IFU instrument for the Anglo-Australian Telescope
Author(s):
Julia J. Bryant;
Joss Bland-Hawthorn;
Jon Lawrence;
Scott Croom;
David Brown;
Sudharshan Venkatesan;
Peter R. Gillingham;
Ross Zhelem;
Robert Content;
Will Saunders;
Nicholas F. Staszak;
Jesse van de Sande;
Warrick Couch;
Sergio Leon-Saval;
Julia Tims;
Richard McDermid;
Adam Schaefer
Show Abstract
Hector[1,2,3] will be the new massively-multiplexed integral field spectroscopy (IFS) instrument for the Anglo-Australian Telescope (AAT) in Australia and the next main dark-time instrument for the observatory. Based on the success of the SAMI instrument, which is undertaking a 3400-galaxy survey, the integral field unit (IFU) imaging fibre bundle (hexabundle) technology under-pinning SAMI is being improved to a new innovative design for Hector. The distribution of hexabundle angular sizes is matched to the galaxy survey properties in order to image 90% of galaxies out to 2 effective radii. 50-100 of these IFU imaging bundles will be positioned by ‘starbug’ robots across a new 3-degree field corrector top end to be purpose-built for the AAT. Many thousand fibres will then be fed into new replicable spectrographs. Fundamentally new science will be achieved compared to existing instruments due to Hector's wider field of view (3 degrees), high positioning efficiency using starbugs, higher spectroscopic resolution (R=3000-5500 from 3727-7761Å, with a possible redder extension later) and large IFUs (up to 30 arcsec diameter with 61-217 fibre cores). A 100,000 galaxy IFS survey with Hector will decrypt how the accretion and merger history and large-scale environment made every galaxy different in its morphology and star formation history. The high resolution, particularly in the blue, will make Hector the only instrument to be able to measure higher-order kinematics for galaxies down to much lower velocity dispersion than in current large IFS galaxy surveys, opening up a wealth of new nearby galaxy science.
VIRUS: first deployment of the massively replicated fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope
Author(s):
Gary J. Hill;
Sarah E. Tuttle;
Brian L. Vattiat;
Hanshin Lee;
Niv Drory;
Andreas Kelz;
Jason Ramsey;
Trent W. Peterson;
D. L. DePoy;
J. L. Marshall;
Karl Gebhardt;
Taylor Chonis;
Gavin Dalton;
Daniel Farrow;
John M. Good;
Dionne M. Haynes;
Briana L. Indahl;
Thomas Jahn;
Hermanus Kriel;
Francesco Montesano;
Harald Nicklas;
Eva Noyola;
Travis Prochaska;
Richard D. Allen;
Ralf Bender;
Guillermo Blanc;
Maximilian H. Fabricius;
Steve Finkelstein;
Martin Landriau;
Phillip J. MacQueen;
M. M. Roth;
R. D. Savage;
Jan M. Snigula;
Heiko Anwad
Show Abstract
The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of 156 identical spectrographs (arrayed as 78 pairs) fed by 35,000 fibers, each 1.5 arcsec diameter, at the focus of the upgraded 10 m Hobby-Eberly Telescope (HET). VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of surveying large areas of sky, spectrally. The VIRUS concept offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments. The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX‡), using 0.8M Lyman-alpha emitting galaxies as tracers. The VIRUS array is undergoing staged deployment during 2016 and 2017. It will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope, and will open up large spectroscopic surveys of the emission line universe for the first time. We will review the production, lessons learned in reaching volume production, characterization, and first deployment of this massive instrument.
VIRUS early installation and commissioning
Author(s):
Sarah E. Tuttle;
Gary J. Hill;
Brian L. Vattiat;
Hanshin Lee;
Niv Drory;
Andreas Kelz;
Jason Ramsey;
Trent Peterson;
Eva Noyola;
Darren L. DePoy;
Jennifer L. Marshall;
Taylor S. Chonis;
Gavin Dalton;
Maximilian Fabricius;
Daniel Farrow;
John M. Good;
Dionne M. Haynes;
Briana Indahl;
Thomas Jahn;
Hermanus Kriel;
Harald Nicklas;
Francesco Montesano;
Travis Prochaska;
Richard D. Allen;
Martin Landriau;
Phillip J. MacQueen;
Martin M. Roth;
Richard Savage;
Jan M. Snigula
Show Abstract
VIRUS is a massively replicated spectrograph built for HETDEX, the Hobby Eberly Telescope Dark Energy Experiment. It consists of 156 channels within 78 units fed by 34944 fibers over the 22 arcminute field of the upgraded HET. VIRUS covers a relatively narrow bandpass (350-550nm) at low resolution (R ~ 700) to target the emission of Lyman-alpha emitters (LAEs) for HETDEX. VIRUS is a first demonstration of industrial style assembly line replication in optical astronomy. Installation and testing of VIRUS units began in November of 2015. This winter we celebrated the first on sky instrument activity of the upgraded HET, using a VIRUS unit and LRS2-R (the upgraded facility Low Resolution Spectrograph for the HET). Here we describe progress in VIRUS installation and commissioning through June 2016. We include early sky data obtained to characterize spectrograph performance and on sky performance of the newly upgraded HET. As part of the instrumentation for first science light at the HET, the IFU fed spectrographs were used to test a full range of telescope system functionality including the field calibration unit (FCU).We also use placement of strategic IFUs to map the new HET field to the fiber placement, and demonstrate actuation of the dithering mechanism key to HETDEX observations.
EMIR at the GTC: results on the commissioning at the telescope
Author(s):
F. Garzón;
N. Castro;
M. Insausti;
E. Manjavacas;
M. Miluzio;
Peter Hammersley;
N. Cardiel;
S. Pascual;
C. González-Fernández;
J. Molgó;
M. Barreto;
P. Fernández;
E. Joven;
P. López;
A. Mato;
H. Moreno;
M. Núñez;
J. Patrón;
J. Rosich;
N. Vega
Show Abstract
We report the results on the EMIR1 (Espectrógrafo Multiobjeto Infra-Rojo) performances after the commissioning period of the instrument at the Gran Telescopio Canarias (GTC). EMIR is one of the first common user instruments for the GTC, the 10 meter telescope operating at the Roque de los Muchachos Observatory (La Palma, Canary Islands, Spain). EMIR is being built by a Consortium of Spanish and French institutes led by the Instituto de Astrofísica de Canarias (IAC). EMIR is primarily designed to be operated as a MOS in the K band, but offers a wide range of observing modes, including imaging and spectroscopy, both long slit and multiobject, in the wavelength range 0.9 to 2.5 μm. The development and fabrication of EMIR is funded by GRANTECAN and the Plan Nacional de Astronomía y Astrofísica (National Plan for Astronomy and Astrophysics, Spain). After an extensive and intensive period of system verification at the IAC, EMIR was shipped to the GTC on May 2016 for its integration at the Nasmyth platform. Once in the observatory, several tests were conducted to ensure the functionality of EMIR at the telescope, in particular that of the ECS (EMIR Control System) which has to be fully embedded into the GCS (GTC Control System) so as to become an integral part of it. During the commissioning, the main capabilities of EMIR and its combined operation with the GTC are tested and the ECS are modified to its final form. This contribution reports on the details of the EMIR operation at the GTC obtained so far, on the first commissioning period.
MEGARA, the new intermediate-resolution optical IFU and MOS for GTC: getting ready for the telescope
Author(s):
A. Gil de Paz;
E. Carrasco;
J. Gallego;
J. Iglesias-Páramo;
R. Cedazo;
M. L. García Vargas;
X. Arrillaga;
J. L. Avilés;
N. Cardiel;
M. A. Carrera;
A. Castillo-Morales;
E. Castillo-Domínguez;
J. M. de la Cruz García;
S. Esteban San Román;
D. Ferrusca;
P. Gómez-Álvarez;
R. Izazaga-Pérez;
B. Lefort;
J. A. López-Orozco;
M. Maldonado;
I. Martínez-Delgado;
I. Morales Durán;
E. Mujica;
G. Páez;
S. Pascual;
A. Pérez-Calpena;
P. Picazo;
A. Sánchez-Penim;
E. Sánchez-Blanco;
S. Tulloch;
M. Velázquez;
J. M. Vílchez;
J. Zamorano;
A. L. Aguerri;
D. Barrado y Naváscues;
E. Bertone;
A. Cava;
J. Cenarro;
M. Chávez;
M. García;
J. García-Rojas;
J. Guichard;
R. González-Delgado;
R. Guzmán;
A. Herrero;
N. Huélamo;
D. H. Hughes;
J. Jiménez-Vicente;
C. Kehrig;
R. A. Marino;
I. Márquez;
J. Masegosa;
Y. D. Mayya;
J. Méndez-Abreu;
M. Mollá;
C. Muñoz-Tuñón;
M. Peimbert;
P. G. Pérez-González;
E. Pérez Montero;
M. Rodríguez;
J. M. Rodríguez-Espinosa;
L. Rodríguez-Merino;
L. Rodríguez-Muñoz;
D. Rosa-González;
J. Sánchez-Almeida;
C. Sánchez Contreras;
P. Sánchez-Blázquez;
F. M. Sánchez Moreno;
S. F. Sánchez;
A. Sarajedini;
S. Silich;
S. Simón-Díaz;
G. Tenorio-Tagle;
E. Terlevich;
R. Terlevich;
S. Torres-Peimbert;
I. Trujillo;
Y. Tsamis;
O. Vega
Show Abstract
MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4m telescope in La Palma that is being built by a Consortium led by UCM (Spain) that also includes INAOE (Mexico), IAA-CSIC (Spain), and UPM (Spain). The instrument is currently finishing AIV and will be sent to GTC on November 2016 for its on-sky commissioning on April 2017. The MEGARA IFU fiber bundle (LCB) covers 12.5x11.3 arcsec2 with a spaxel size of 0.62 arcsec while the MEGARA MOS mode allows observing up to 92 objects in a region of 3.5x3.5 arcmin2 around the IFU. The IFU and MOS modes of MEGARA will provide identical intermediate-to-high spectral resolutions (RFWHM~6,000, 12,000 and 18,700, respectively for the low-, mid- and high-resolution Volume Phase Holographic gratings) in the range 3700-9800ÅÅ. An x-y mechanism placed at the pseudo-slit position allows (1) exchanging between the two observing modes and (2) focusing the spectrograph for each VPH setup. The spectrograph is a collimator-camera system that has a total of 11 VPHs simultaneously available (out of the 18 VPHs designed and being built) that are placed in the pupil by means of a wheel and an insertion mechanism. The custom-made cryostat hosts a 4kx4k 15-μm CCD. The unique characteristics of MEGARA in terms of throughput and versatility and the unsurpassed collecting are of GTC make of this instrument the most efficient tool to date to analyze astrophysical objects at intermediate spectral resolutions. In these proceedings we present a summary of the instrument characteristics and the results from the AIV phase. All subsystems have been successfully integrated and the system-level AIV phase is progressing as expected.
MIRADAS for the Gran Telescopio Canarias
Author(s):
Stephen S. Eikenberry;
Steven Nicholas Raines;
Richard Deno Stelter;
Alan Garner;
Yigit Dallilar;
Kendall Ackley;
John Greg Bennett;
Charles H. Murphey;
Paola Miller;
David Tooke;
Luke Williams;
Brian Chinn;
Scott A. Mullin;
Sidney L. Schofield;
Craig D. Warner;
Frank Varosi;
Bo Zhao;
Sophia A. Eikenberry;
Claudia Vega;
Hipatia V. Donoso;
Josep Sabater;
José María Gómez;
Jordi Torra;
Josefina Rosich Minguell;
Francisco Garzón López;
Nicolás Cardiel;
Jesús Gallego Maestro;
Antonio Marín-Franch;
Julio Galipienzo;
Miguel Ángel Carrera Astigarraga;
Greg J. Fitzgerald;
Ian Prees;
Todd M. Stolberg;
Peter A. Kornik;
Anamparambu N. Ramaprakash;
Mahesh P. Burse;
Sujit P. Punnadi;
P. Hammersley
Show Abstract
The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS, a near-infrared multi-object echelle spectrograph operating at spectral resolution R=20,000 over the 1-2.5μm bandpass) was selected by the Gran Telescopio Canarias (GTC) partnership as the next-generation near-infrared spectrograph for the world's largest optical/infrared telescope, and is being developed by an international consortium. The MIRADAS consortium includes the University of Florida, Universidad de Barcelona, Universidad Complutense de Madrid, Instituto de Astrofísica de Canarias, and Institut d'Estudis Espacials de Catalunya, as well as probe arm industrial partner A-V-S (Spain), with more than 45 Science Working Group members in 10 institutions primarily in Spain, Mexico, and the USA. In this paper, we review the overall system design and project status for MIRADAS during its early fabrication phase in 2016.
Prime Focus Spectrograph (PFS) for the Subaru telescope: overview, recent progress, and future perspectives
Author(s):
Naoyuki Tamura;
Naruhisa Takato;
Atsushi Shimono;
Yuki Moritani;
Kiyoto Yabe;
Yuki Ishizuka;
Akitoshi Ueda;
Yukiko Kamata;
Hrand Aghazarian;
Stéphane Arnouts;
Gabriel Barban;
Robert H. Barkhouser;
Renato C. Borges;
David F. Braun;
Michael A. Carr;
Pierre-Yves Chabaud;
Yin-Chang Chang;
Hsin-Yo Chen;
Masashi Chiba;
Richard C. Y. Chou;
You-Hua Chu;
Judith Cohen;
Rodrigo P. de Almeida;
Antonio C. de Oliveira Sr.;
Ligia S. de Oliveira;
Richard G. Dekany;
Kjetil Dohlen;
Jesulino B. dos Santos;
Leandro H. dos Santos;
Richard Ellis;
Maximilian Fabricius;
Didier Ferrand;
Décio Ferreira;
Mirek Golebiowski;
Jenny E. Greene;
Johannes Gross;
James E. Gunn Sr.;
Randolph Hammond;
Albert Harding;
Murdock Hart;
Timothy M. Heckman;
Christopher M. Hirata;
Paul Ho;
Stephen C. Hope;
Larry Hovland;
Shu-Fu Hsu;
Yen-Shan Hu;
Ping-Jie Huang;
Marc Jaquet;
Yipeng Jing;
Jennifer Karr;
Masahiko Kimura;
Matthew E. King;
Eiichiro Komatsu;
Vincent Le Brun;
Olivier Le Fèvre;
Arnaud Le Fur;
David Le Mignant;
Hung-Hsu Ling;
Craig P. Loomis;
Robert H. Lupton;
Fabrice Madec;
Peter Mao;
Lucas S. Marrara;
Claudia Mendes de Oliveira;
Yosuke Minowa;
Chaz Morantz;
Hitoshi Murayama;
Graham J. Murray;
Youichi Ohyama;
Joseph Orndorff;
Sandrine Pascal;
Jefferson M. Pereira;
Daniel Reiley;
Martin Reinecke;
Andreas Ritter;
Mitsuko Roberts;
Mark A. Schwochert;
Michael D. Seiffert;
Stephen A. Smee;
Laerte Sodre Jr.;
David N. Spergel;
Aaron J. Steinkraus;
Michael A. Strauss;
Christian Surace;
Yasushi Suto;
Nao Suzuki;
John Swinbank;
Philip J. Tait;
Masahiro Takada;
Tomonori Tamura;
Yoko Tanaka;
Laurence Tresse;
Orlando Verducci Jr.;
Didier Vibert;
Clement Vidal;
Shiang-Yu Wang;
Chih-Yi Wen;
Chi-Hung Yan;
Naoki Yasuda
Show Abstract
PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~1.6 - 2.7Å. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.
4MOST: the 4-metre Multi-Object Spectroscopic Telescope project at preliminary design review
Author(s):
Roelof S. de Jong;
Samuel C. Barden;
Olga Bellido-Tirado;
Joar G. Brynnel;
Steffen Frey;
Domenico Giannone;
Roger Haynes;
Diana Johl;
Daniel Phillips;
Olivier Schnurr;
Jakob C. Walcher;
Roland Winkler;
Wolfgang R. Ansorge;
Sofia Feltzing;
Richard G. McMahon;
Gabriella Baker;
Patrick Caillier;
Tom Dwelly;
Wolfgang Gaessler;
Olaf Iwert;
Holger G. Mandel;
Nikolai A. Piskunov;
Johan H. Pragt;
Nicholas A. Walton;
Thomas Bensby;
Maria Bergemann;
Cristina Chiappini;
Norbert Christlieb;
Maria-Rosa L. Cioni;
Simon Driver;
Alexis Finoguenov;
Amina Helmi;
Michael J. Irwin;
Francisco-Shu Kitaura;
Jean-Paul Kneib;
Jochen Liske;
Andrea Merloni;
Ivan Minchev;
Johan Richard;
Else Starkenburg
Show Abstract
We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R~20,000) and two medium resolution (R~5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a unique operations concept in which 5-year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey.
Mauna Kea Spectrographic Explorer (MSE): a conceptual design for multi-object high resolution spectrograph
Author(s):
Kai Zhang;
Yongtian Zhu;
Zhongwen Hu
Show Abstract
The Maunakea Spectroscopic Explorer (MSE) project will transform the CFHT 3.6m optical telescope into a 10m class dedicated multi-object spectroscopic facility, with an ability to simultaneously measure thousands of objects with a spectral resolution range spanning 2,000 to 40,000. MSE will develop two spectrographic facilities to meet the science requirements. These are respectively, the Low/Medium Resolution spectrographs (LMRS) and High Resolution spectrographs (HRS). Multi-object high resolution spectrographs with total of 1,156 fibers is a big challenge, one that has never been attempted for a 10m class telescope. To date, most spectral survey facilities work in single order low/medium resolution mode, and only a few Wide Field Spectrographs (WFS) provide a cross-dispersion high resolution mode with a limited number of orders. Nanjing Institute of Astronomical Optics and Technology (NIAOT) propose a conceptual design with the use of novel image slicer arrays and single order immersed Volume Phase Holographic (VPH) grating for the MSE multi-object high resolution spectrographs. The conceptual scheme contains six identical fiber-link spectrographs, each of which simultaneously covers three restricted bands (λ/30, λ/30, λ/15) in the optical regime, with spectral resolution of 40,000 in Blue/Visible bands (400nm / 490nm) and 20,000 in Red band (650nm). The details of the design is presented in this paper.
ULTIMATE: a deployable multiple integral field unit for Subaru
Author(s):
S. C. Ellis;
Ross Zhelem;
David Brown;
Nicholas F. Staszak;
Chris Lidman;
David M. Nataf;
Andrew R. Casey;
Pascal Xavier;
Andrew Sheinis;
Peter Gillingham;
Julia Tims;
Jon Lawrence;
Julia Bryant;
Rob Sharp
Show Abstract
ULTIMATE is an instrument concept under development at the AAO, for the Subaru Telescope, which will have the unique combination of ground layer adaptive optics feeding multiple deployable integral field units. This will allow ULTIMATE to probe unexplored parameter space, enabling science cases such as the evolution of galaxies at z ~ 0:5 to 1.5, and the dark matter content of the inner part of our Galaxy. ULTIMATE will use Starbugs to position between 7 and 13 IFUs over a 14 × 8 arcmin field-of-view, pro- vided by a new wide-field corrector. All Starbugs can be positioned simultaneously, to an accuracy of better than 5 milli-arcsec within the typical slew-time of the telescope, allowing for very efficient re-configuration between observations. The IFUs will feed either the near-infrared nuMOIRCS or the visible/ near-infrared PFS spectrographs, or both. Future possible upgrades include the possibility of purpose built spectrographs and incorporating OH suppression using fibre Bragg gratings. We describe the science case and resulting design requirements, the baseline instrument concept, and the expected performance of the instrument.
Cosmological surveys with multi-object spectrographs
Author(s):
Matthew Colless
Show Abstract
Multi-object spectroscopy has been a key technique contributing to the current era of ‘precision cosmology.’ From the first exploratory surveys of the large-scale structure and evolution of the universe to the current generation of superbly detailed maps spanning a wide range of redshifts, multi-object spectroscopy has been a fundamentally important tool for mapping the rich structure of the cosmic web and extracting cosmological information of increasing variety and precision. This will continue to be true for the foreseeable future, as we seek to map the evolving geometry and structure of the universe over the full extent of cosmic history in order to obtain the most precise and comprehensive measurements of cosmological parameters. Here I briefly summarize the contributions that multi-object spectroscopy has made to cosmology so far, then review the major surveys and instruments currently in play and their prospects for pushing back the cosmological frontier. Finally, I examine some of the next generation of instruments and surveys to explore how the field will develop in coming years, with a particular focus on specialised multi-object spectrographs for cosmology and the capabilities of multi-object spectrographs on the new generation of extremely large telescopes.
Instrumentation progress at the Giant Magellan Telescope project
Author(s):
George H. Jacoby;
R. Bernstein;
A. Bouchez;
M Colless;
Jeff Crane;
D. DePoy;
B. Espeland;
Tyson Hare;
D. Jaffe;
J. Lawrence;
J. Marshall;
P. McGregor;
Stephen Shectman;
R. Sharp;
A. Szentgyorgyi;
Alan Uomoto;
B. Walls
Show Abstract
Instrument development for the 24m Giant Magellan Telescope (GMT) is described: current activities, progress, status, and schedule. One instrument team has completed its preliminary design and is currently beginning its final design (GCLEF, an optical 350-950 nm, high-resolution and precision radial velocity echelle spectrograph). A second instrument team is in its conceptual design phase (GMACS, an optical 350-950 nm, medium resolution, 6-10 arcmin field, multi-object spectrograph). A third instrument team is midway through its preliminary design phase (GMTIFS, a near-IR YJHK diffraction-limited imager/integral-field-spectrograph), focused on risk reduction prototyping and design optimization. A fourth instrument team is currently fabricating the 5 silicon immersion gratings needed to begin its preliminary design phase (GMTNIRS, a simultaneous JHKLM high-resolution, AO-fed, echelle spectrograph). And, another instrument team is focusing on technical development and prototyping (MANIFEST, a facility robotic, multifiber feed, with a 20 arcmin field of view). In addition, a medium-field (6 arcmin, 0.06 arcsec/pix) optical imager will support telescope and AO commissioning activities, and will excel at narrow-band imaging. In the spirit of advancing synergies with other groups, the challenges of running an ELT instrument program and opportunities for cross-ELT collaborations are discussed.
Thirty Meter Telescope science instruments: a status report
Author(s):
Luc Simard;
Brent Ellerbroek;
Ravinder Bhatia;
Matthew Radovan;
Eric Chisholm
Show Abstract
An overview of the current status of the science instruments for the Thirty Meter Telescope is presented. Three first-light instruments as well as a science calibration unit for AO-assisted instruments are under development. Developing instrument collaborations that can design and build these challenging instruments remains an area of intense activity. In addition to the instruments themselves, a preliminary design for a facility cryogenic cooling system based on gaseous helium turbine expanders has been completed. This system can deliver a total of 2.4 kilowatts of cooling power at 65K to the instruments with essentially no vibrations. Finally, the process for developing future instruments beyond first light has been extensively discussed and will get under way in early 2017.
The Infrared Imaging Spectrograph (IRIS) for TMT: instrument overview
Author(s):
James E. Larkin;
Anna M. Moore;
Shelley A. Wright;
James E. Wincentsen;
David Anderson;
Eric M. Chisholm;
Richard G. Dekany;
Jennifer S. Dunn;
Brent L. Ellerbroek;
Yutaka Hayano;
Andrew C. Phillips;
Luc Simard;
Roger Smith;
Ryuji Suzuki;
Robert W. Weber;
Jason L. Weiss;
Kai Zhang
Show Abstract
IRIS is a near-infrared (0.84 to 2.4 micron) integral field spectrograph and wide-field imager being developed for first light with the Thirty Meter Telescope (TMT). It mounts to the advanced adaptive optics (AO) system NFIRAOS and has integrated on-instrument wavefront sensors (OIWFS) to achieve diffraction-limited spatial resolution at wavelengths longer than 1 μm. With moderate spectral resolution (R ~ 4000 – 8,000) and large bandpass over a continuous field of view, IRIS will open new opportunities in virtually every area of astrophysical science. It will be able to resolve surface features tens of kilometers across Titan, while also mapping the most distant galaxies at the scale of an individual star forming region. This paper summarizes the entire design and capabilities, and includes the results from the nearly completed preliminary design phase.
The E-ELT first light spectrograph HARMONI: capabilities and modes
Author(s):
Niranjan A. Thatte;
Fraser Clarke;
Ian Bryson;
Hermine Shnetler;
Matthias Tecza;
Thierry Fusco;
Roland M. Bacon;
Johan Richard;
Evencio Mediavilla;
Benoît Neichel;
Santiago Arribas;
Begoña Garcia-Lorenzo;
Christopher J. Evans;
Alban Remillieux;
Kacem El Madi;
Jose Miguel Herreros;
Dave Melotte;
Kieran O'Brien;
Ian A. Tosh;
Joël Vernet;
Peter Hammersley;
Derek J. Ives;
Gert Finger;
Ryan Houghton;
Dimitra Rigopoulou;
James D. Lynn;
Jamie R. Allen;
Simon D. Zieleniewski;
Sarah Kendrew;
Vanessa Ferraro-Wood;
Arlette Pécontal-Rousset;
Johan Kosmalski;
Florence Laurent;
Magali Loupias;
Laure Piqueras;
Edgar Renault;
Jeremy Blaizot;
Eric Daguisé;
Jean-Emmanuel Migniau;
Aurélien Jarno;
Andy Born;
Angus M. Gallie;
David M. Montgomery;
David Henry;
Noah Schwartz;
William Taylor;
Gérard Zins;
Luis Fernando Rodríguez-Ramos;
Miguel Cagigas;
Giuseppina Battaglia;
Refael Rebolo López;
Elvio Hernández Suárez;
José Vicente Gigante-Ripoll;
Javier Piqueras López;
Montserrat Villa Martin;
Carlos Correia;
Sandrine Pascal;
Leonardo Blanco;
Pascal Vola;
Benoit Epinat;
Celine Peroux;
Arthur Vigan;
Kjetil Dohlen;
Jean-Francois Sauvage;
Martin Lee;
Alexis Carlotti;
Christophe Verinaud;
Tim Morris;
Richard Myers;
Andrew Reeves;
Mark Swinbank;
Ariadna Calcines;
Marrie Larrieu
Show Abstract
HARMONI is the E-ELT’s first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers (R ~3500, 7500 and 20000) and instantaneous wavelength coverage spanning the 0.5 – 2.4 μm wavelength range of the instrument. In autumn 2015, the HARMONI project started the Preliminary Design Phase, following signature of the contract to design, build, test and commission the instrument, signed between the European Southern Observatory and the UK Science and Technology Facilities Council. Crucially, the contract also includes the preliminary design of the HARMONI Laser Tomographic Adaptive Optics system. The instrument’s technical specifications were finalized in the period leading up to contract signature. In this paper, we report on the first activity carried out during preliminary design, defining the baseline architecture for the system, and the trade-off studies leading up to the choice of baseline.
GMTIFS: The Giant Magellan Telescope integral fields spectrograph and imager
Author(s):
Rob Sharp;
G. Bloxham;
R. Boz;
D. Bundy;
J. Davies;
B. Espeland;
B. Fordham;
J. Hart;
N. Herrald;
J. Nielsen;
A. Vaccarella;
C. Vest;
P. Young;
P. McGregor
Show Abstract
GMTIFS is the first-generation adaptive optics integral-field spectrograph for the GMT, having been selected through a competitive review process in 2011. The GMTIFS concept is for a workhorse single-object integral-field spectrograph, operating at intermediate resolution (R~5,000 and 10,000) with a parallel imaging channel. The IFS offers variable spaxel scales to Nyquist sample the diffraction limited GMT PSF from λ ~ 1-2.5 μm as well as a 50 mas scale to provide high sensitivity for low surface brightness objects. The GMTIFS will operate with all AO modes of the GMT (Natural guide star - NGSAO, Laser Tomography – LTAO, and, Ground Layer - GLAO) with an emphasis on achieving high sky coverage for LTAO observations. We summarize the principle science drivers for GMTIFS and the major design concepts that allow these goals to be achieved.
Status of the mid-infrared E-ELT imager and spectrograph METIS
Author(s):
Bernhard R. Brandl;
Tibor Agócs;
Gabby Aitink-Kroes;
Thomas Bertram;
Felix Bettonvil;
Roy van Boekel;
Olivier Boulade;
Markus Feldt;
Alistair Glasse;
Adrian Glauser;
Manuel Güdel;
Norma Hurtado;
Rieks Jager;
Matthew A. Kenworthy;
Michael Mach;
Jeff Meisner;
Michael Meyer;
Eric Pantin;
Sascha Quanz;
Hans Martin Schmid;
Remko Stuik;
Auke Veninga;
Christoffel Waelkens
Show Abstract
METIS is one the first three instruments on the E-ELT. Apart from diffraction limited imaging, METIS will provide coronagraphy and medium resolution slit spectroscopy over the 3 – 19μm range, as well as high resolution (R ~ 100,000) integral field spectroscopy from 2.9 – 5.3μm, including a mode with extended instantaneous wavelength coverage. The unique combination of these observing capabilities, makes METIS the ideal instrument for the study of circumstellar disks and exoplanets, among many other science areas. In this paper we provide an update of the relevant science drivers, the METIS observing modes, the status of the simulator and the data analysis. We discuss the preliminary design of the optical system, which is driven by the need to calibrate observations at thermal IR wavelengths on a six-mirror ELT. We present the expected adaptive optics performance and the measures taken to enable high contrast imaging. We describe the opto-mechanical system, the location of METIS on the Nasmyth instrument platform, and conclude with an update on critical subsystem components, such as the immersed grating and the focal plane detectors. In summary, the work on METIS has taken off well and is on track for first light in 2025.
GMTNIRS: progress toward the Giant Magellan Telescope near-infrared spectrograph
Author(s):
Daniel T. Jaffe;
Stuart Barnes;
Cynthia Brooks;
Hanshin Lee;
Gregory Mace;
Soojong Pak;
Byeong-Gon Park;
Chan Park
Show Abstract
GMTNIRS is a first-generation instrument for the Giant Magellan Telescope. It is a high-resolution spectrograph that will cover the 1.15-5.3 μm range in a single exposure with R=60,000 in the J, H, and K bands and R=85,000 in the L and M bands. It resides on the GMT’s rotating instrument platform and employs the facility adaptive optics system. The GMTNIRS design is evolving in response to emerging science problems, particularly in the area of exoplanet atmospheres. Our design revisions also derive lessons from GMTNIRS’ highly successful forerunner instrument, IGRINS. Technical changes also drive evolution of the design. It has proven impractical to manufacture 200mm long immersion gratings at the necessary precision. The success of primary mirror phasing efforts has removed the need for a very wide entrance slit that we would have needed to accommodate the Airy pattern of individual segments at the shortest operating wavelengths. The high efficiency of our double-side coated JWST grisms introduces the possibility of transmissive cross-dispersers at L and M. These changes move us toward a design with almost the same R as presented in our previous work but with a much more compact physical envelope. We will report on the optimization of the instrument design with these technical changes in mind. We are also producing the critical Si immersion gratings. The grating production is well under way and includes manufacture of H and K gratings and process development for the precision needed in the J band and for the manufacture of larger gratings for the L and M band. The development of GMTNIRS is on track with the results from IGRINS and the progress in the lab giving us substantial assurance that the new instrument can meet its performance goals.
The GMT-Consortium Large Earth Finder (G-CLEF): an optical Echelle spectrograph for the Giant Magellan Telescope (GMT)
Author(s):
Andrew Szentgyorgyi;
Daniel Baldwin;
Stuart Barnes;
Jacob Bean;
Sagi Ben-Ami;
Patricia Brennan;
Jamie Budynkiewicz;
Moo-Young Chun;
Charlie Conroy;
Jeffrey D. Crane;
Harland Epps;
Ian Evans;
Janet Evans;
Jeff Foster;
Anna Frebel;
Thomas Gauron;
Dani Guzmán;
Tyson Hare;
Bi-Ho Jang;
Jeong-Gyun Jang;
Andres Jordan;
Jihun Kim;
Kang-Miin Kim;
Claudia Mendes Mendes de Oliveira;
Mercedes Lopez-Morales;
Kenneth McCracken;
Stuart McMuldroch;
Joseph Miller;
Mark Mueller;
Jae Sok Oh;
Cem Onyuksel;
Mark Ordway;
Byeong-Gon Park;
Chan Park;
Sung-Joon Park;
Charles Paxson;
David Phillips;
David Plummer;
William Podgorski;
Andreas Seifahrt;
Daniel Stark;
Joao Steiner;
Alan Uomoto;
Ronald Walsworth;
Young-Sam Yu
Show Abstract
The GMT-Consortium Large Earth Finder (G-CLEF) will be a cross-dispersed, optical band echelle spectrograph to be delivered as the first light scientific instrument for the Giant Magellan Telescope (GMT) in 2022. G-CLEF is vacuum enclosed and fiber-fed to enable precision radial velocity (PRV) measurements, especially for the detection and characterization of low-mass exoplanets orbiting solar-type stars. The passband of G-CLEF is broad, extending from 3500Å to 9500Å. This passband provides good sensitivity at blue wavelengths for stellar abundance studies and deep red response for observations of high-redshift phenomena. The design of G-CLEF incorporates several novel technical innovations. We give an overview of the innovative features of the current design. G-CLEF will be the first PRV spectrograph to have a composite optical bench so as to exploit that material’s extremely low coefficient of thermal expansion, high in-plane thermal conductivity and high stiffness-to-mass ratio. The spectrograph camera subsystem is divided into a red and a blue channel, split by a dichroic, so there are two independent refractive spectrograph cameras. The control system software is being developed in model-driven software context that has been adopted globally by the GMT. G-CLEF has been conceived and designed within a strict systems engineering framework. As a part of this process, we have developed a analytical toolset to assess the predicted performance of G-CLEF as it has evolved through design phases.
EELT-HIRES the high-resolution spectrograph for the E-ELT
Author(s):
A. Marconi;
P. Di Marcantonio;
V. D'Odorico;
S. Cristiani;
R. Maiolino;
E. Oliva;
L. Origlia;
M. Riva;
L. Valenziano;
F. M. Zerbi;
M. Abreu;
V. Adibekyan;
C. Allende Prieto;
P. J. Amado;
W. Benz;
I. Boisse;
X. Bonfils;
F. Bouchy;
L. Buchhave;
D. Buscher;
A. Cabral;
B. L. Canto Martins;
A. Chiavassa;
J. Coelho;
L. B. Christensen;
E. Delgado-Mena;
J. R. de Medeiros;
I. Di Varano;
P. Figueira;
M. Fisher;
J. P. U. Fynbo;
A. C. H. Glasse;
M. Haehnelt;
C. Haniff;
C. J. Hansen;
A. Hatzes;
P. Huke;
A. J. Korn;
I. C. Leão;
J. Liske;
C. Lovis;
P. Maslowski;
I. Matute;
R. A. McCracken;
C. J. A. P. Martins;
M. J. P. F. G. Monteiro;
S. Morris;
T. Morris;
H. Nicklas;
A. Niedzielski;
N. J. Nunes;
E. Palle;
P. M. Parr-Burman;
V. Parro;
I. Parry;
F. Pepe;
N. Piskunov;
Didier Queloz;
A. Quirrenbach;
R. Rebolo Lopez;
A. Reiners;
D. T. Reid;
N. Santos;
W. Seifert;
S. Sousa;
H. C. Stempels;
K. Strassmeier;
X. Sun;
S. Udry;
L. Vanzi;
M. Vestergaard;
M. Weber;
E. Zackrisson
Show Abstract
The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.
The E-ELT multi-object spectrograph: latest news from MOSAIC
Author(s):
F. Hammer;
S. Morris;
L. Kaper;
B. Barbuy;
J. G. Cuby;
M. Roth;
P. Jagourel;
C. J. Evans;
M. Puech;
E. Fitzsimons;
G. Dalton;
M. Rodrigues
Show Abstract
There are 8000 galaxies, including 1600 at z ≥ 1.6, which could be simultaneously observed in an E-ELT field of view of 40 arcmin2. A considerable fraction of astrophysical discoveries require large statistical samples, which can only be obtained with multi-object spectrographs (MOS). MOSAIC will provide a vast discovery space, enabled by a multiplex of 200 and spectral resolving powers of R=5000 and 20000. MOSAIC will also offer the unique capability of more than 10 `high-definition' (multi-object adaptive optics, MOAO) integral-field units, optimised to investigate the physics of the sources of reionization. The combination of these modes will make MOSAIC the world-leading MOS facility, contributing to all fields of contemporary astronomy, from extra-solar planets, to the study of the halo of the Milky Way and its satellites, and from resolved stellar populations in nearby galaxies out to observations of the earliest ‘first-light’ structures in the Universe. It will also study the distribution of the dark and ordinary matter at all scales and epochs of the Universe. Recent studies of critical technical issues such as sky-background subtraction and MOAO have demonstrated that such a MOS is feasible with state-of-the-art technology and techniques. Current studies of the MOSAIC team include further trade-offs on the wavelength coverage, a solution for compensating for the non-telecentric new design of the telescope, and tests of the saturation of skylines especially in the near-IR bands. In the 2020s the E-ELT will become the world's largest optical/IR telescope, and we argue that it has to be equipped as soon as possible with a MOS to provide the most efficient, and likely the best way to follow-up on James Webb Space Telescope (JWST) observations.
SpUpNIC (Spectrograph Upgrade: Newly Improved Cassegrain) on the South African Astronomical Observatory's 74-inch telescope
Author(s):
Lisa A. Crause;
Dave Carter;
Alroy Daniels;
Geoff Evans;
Piet Fourie;
David Gilbank;
Malcolm Hendricks;
Willie Koorts;
Deon Lategan;
Egan Loubser;
Sharon Mouries;
James E. O'Connor;
Darragh E. O'Donoghue;
Stephen Potter;
Craig Sass;
Amanda A. Sickafoose;
John Stoffels;
Pieter Swanevelder;
Keegan Titus;
Carel van Gend;
Martin Visser;
Hannah L. Worters
Show Abstract
SpUpNIC (Spectrograph Upgrade: Newly Improved Cassegrain) is the extensively upgraded Cassegrain Spectrograph on the South African Astronomical Observatory's 74-inch (1.9-m) telescope. The inverse-Cassegrain collimator mirrors and woefully inefficient Maksutov-Cassegrain camera optics have been replaced, along with the CCD and SDSU controller. All moving mechanisms are now governed by a programmable logic controller, allowing remote configuration of the instrument via an intuitive new graphical user interface. The new collimator produces a larger beam to match the optically faster Folded-Schmidt camera design and nine surface-relief diffraction gratings offer various wavelength ranges and resolutions across the optical domain. The new camera optics (a fused silica Schmidt plate, a slotted fold flat and a spherically figured primary mirror, both Zerodur, and a fused silica field-flattener lens forming the cryostat window) reduce the camera’s central obscuration to increase the instrument throughput. The physically larger and more sensitive CCD extends the available wavelength range; weak arc lines are now detectable down to 325 nm and the red end extends beyond one micron. A rear-of-slit viewing camera has streamlined the observing process by enabling accurate target placement on the slit and facilitating telescope focus optimisation. An interactive quick-look data reduction tool further enhances the user-friendliness of SpUpNI
Faint skylines in the near-infrared: observational constraint for IFU instruments
Author(s):
H. Flores;
M. Rodrigues;
M. Puech;
Y. Yang;
F. Hammer
Show Abstract
The amplitudes and scales of spatial variations in the skylines can be a potential limit of the telescopes performance, because the study of the extremely faint objects requires a careful correction for the residual of the skylines if they are corrected. Using observations from the VLT/KMOS instrument, we have studied the spatial and temporal behavior of two faint skylines (10 to 80 times fainter than the strong skyline in the spectral window) and the effect of the skylines in the determination of the kinematics maps of distant galaxies. Using nine consecutives exposures of ten minutes. We found that the flux of the brighter skylines changes rapidly spatially and temporally, 5 to 10% and up to 15%, respectively. For the faint skyline, the fluctuations have a spatial and temporal amplitude up to 100%. The effect of the residual of the skyline on the velocity field of distant galaxies becomes dramatic when the emission line is faint (equivalent width equal to 15 A). All the kinematic information is lost. The shape and the centroid of the emission line change from spaxel to spaxel. This preliminary result needs to be extended; by continuing the simulation, in order to determine, the minimum flux that allows to recover of the kinematic information at different resolutions. Allowing to find the possible relation between spectral resolution and flux of the emission line. Our goal is to determine which is the best spectral resolution in the infrared to observe the distant galaxies with integral field spectrographs. Finding the best compromise between spectral resolution and the detection limit of the spectrograph.
Regaining the FORS: making optical ground-based transmission spectroscopy of exoplanets with VLT+FORS2 possible again
Author(s):
Henri M. J. Boffin;
Elyar Sedaghati;
Guillaume Blanchard;
Oscar Gonzalez;
Sabine Moehler;
Neale Gibson;
Mario van den Ancker;
Jonathan Smoker;
Joseph Anderson;
Christian Hummel;
Danuta Dobrzycka;
Alain Smette;
Gero Rupprecht
Show Abstract
Transmission spectroscopy facilitates the detection of molecules and/or clouds in the atmospheres of exoplanets. Such studies rely heavily on space-based or large ground-based observatories, as one needs to perform time-resolved, high signal-to-noise spectroscopy. The FORS2 instrument at ESO's Very Large Telescope is the obvious choice for performing such studies, and was indeed pioneering the field in 2010. After that, however, it was shown to suffer from systematic errors caused by the Longitudinal Atmospheric Dispersion Corrector (LADC). This was successfully addressed, leading to a renewed interest for this instrument as shown by the number of proposals submitted to perform transmission spectroscopy of exoplanets. We present here the context, the problem and how we solved it, as well as the recent results obtained. We finish by providing tips for an optimum strategy to do transmission spectroscopy with FORS2, in the hope that FORS2 may become the instrument of choice for ground-based transmission spectroscopy of exoplanets.
Mosaic3: a red-sensitive upgrade for the prime focus camera at the Mayall 4m telescope
Author(s):
Arjun Dey;
David Rabinowitz;
Armin Karcher;
Chris Bebek;
Charles Baltay;
David Sprayberry;
Frank Valdes;
Bob Stupak;
John Donaldson;
Will Emmet;
Tom Hurteau;
Behzad Abareshi;
Bob Marshall;
Dustin Lang;
Mike Fitzpatrick;
Phil Daly;
Dick Joyce;
David Schlegel;
Heidi Schweiker;
Lori Allen;
Bob Blum;
Michael Levi
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction and will be used to measure the expansion history of the Universe using the Baryon Acoustic Oscillation (BAO) technique and the growth of structure using redshift-space distortions (RSD). The spectra of 30 million galaxies over 14000 sq deg will be measured over the course of the experiment. In order to provide spectroscopic targets for the DESI survey, we are carrying out a three-band (g,r,z ) imaging survey of the sky using the NOAO 4-m telescopes at Kitt Peak National Observatory (KPNO) and the Cerro Tololo Interamerican Observatory (CTIO). At KPNO, we will use an upgraded version of the Mayall 4m telescope prime focus camera, Mosaic3, to carry out a z-band survey of the Northern Galactic Cap at declinations δ≥+30 degrees. By equipping an existing Dewar with four 4kx4k fully depleted CCDs manufactured by the Lawrence Berkeley National Laboratory (LBNL), we increased the z-band throughput of the system by a factor of 1.6. These devices have the thickest active area fielded at a telescope. The Mosaic3 z-band survey will be complemented by g-band and r-band observations using the Bok telescope and 90 Prime imager on Kitt Peak. We describe the upgrade and performance of the Mosaic3 instrument and the scope of the northern survey.
FIFI-LS diffraction grating vibration on SOFIA
Author(s):
Felix Rebell;
Simon Beckmann;
Aaron Bryant;
Sebastian Colditz;
Christian Fischer;
Fabio Fumi;
Rainer Hoenle;
Norbert Geis;
Christof Iserlohe;
Randolf Klein;
Alfred Krabbe;
Leslie Looney;
Albrecht Poglitsch;
Walfried Raab;
Maureen Savage
Show Abstract
FIFI-LS (the Field Imaging Far Infrared Line Spectrometer for SOFIA) was successfully commissioned in 2014 during six flights on SOFIA. The observed wavelengths are set by rotating reflective gratings. In flight these gratings and their rotating mechanisms are exposed to vibrations. To quantify these vibrations, an acceleration sensor was placed on the exterior of the instrument. Simultaneously, the angle sensor of the grating was read out to analyze the movement of the grating. Based on this data, lab measurements were conducted to evaluate the effect of the vibrations on the image quality of FIFI-LS. The submitted paper will present the measured data and show the results of the analysis.
The nuMOIRCS project: detector upgrade overview and early commissioning results
Author(s):
Josh Walawender;
Matthew Wung;
Maximilian Fabricius;
Ichi Tanaka;
Nobuo Arimoto;
David Cook;
Brian Elms;
Yasuhito Hashiba;
Yen-Sang Hu;
Ikuru Iwata;
Tetsuo Nishimura;
Koji Omata;
Naruhisa Takato;
Shiang-Yu Wang;
Mark Weber
Show Abstract
In 2014 and 2015 the Multi-Object InfraRed Camera and Spectrograph (MOIRCS) instrument at the Subaru Telescope on Maunakea is underwent a significant modernization and upgrade project. We upgraded the two Hawaii2 detectors to Hawaii2-RG models, modernized the cryogenic temperature control system, and rewrote much of the instrument control software. The detector upgrade replaced the Hawaii2 detectors which use the Tohoku University Focal Plane Array Controller (TUFPAC) electronics with Hawaii2-RG detectors using SIDECAR ASIC (a fully integrated FPA controller system-on-a-chip) and a SAM interface card. We achieved an improvement in read noise by a factor of about 2 with this detector and electronics upgrade. The cryogenic temperature control upgrade focused on modernizing the components and making the procedures for warm up and cool down of the instrument safer. We have moved PID control loops out of the instrument control software and into Lakeshore model 336 cryogenic temperature controllers and have added interlocks on the warming systems to prevent overheating of the instrument. Much of the instrument control software has also been re-written. This was necessitated by the different interface to the detector electronics (ASIC and SAM vs. TUFPAC) and by the desire to modernize the interface to the telescope control software which has been updated to Subaru's "Gen2" system since the time of MOIRCS construction and first light. The new software is also designed to increase reliability of operation of the instrument, decrease overheads, and be easier for night time operators and support astronomers to use.
Upgraded cameras for the HESS imaging atmospheric Cherenkov telescopes
Author(s):
Gianluca Giavitto;
Terry Ashton;
Arnim Balzer;
David Berge;
Francois Brun;
Thomas Chaminade;
Eric Delagnes;
Gérard Fontaine;
Matthias Füßling;
Berrie Giebels;
Jean-François Glicenstein;
Tobias Gräber;
James Hinton;
Albert Jahnke;
Stefan Klepser;
Marko Kossatz;
Axel Kretzschmann;
Valentin Lefranc;
Holger Leich;
Hartmut Lüdecke;
Iryna Lypova;
Pascal Manigot;
Vincent Marandon;
Emmanuel Moulin;
Mathieu de Naurois;
Patrick Nayman;
Marek Penno;
Duncan Ross;
David Salek;
Markus Schade;
Thomas Schwab;
Rachel Simoni;
Christian Stegmann;
Constantin Steppa;
Julian Thornhill;
François Toussnel
Show Abstract
The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes, sensitive to cosmic gamma rays of energies between ~30 GeV and several tens of TeV. Four of them started operations in 2003 and their photomultiplier tube (PMT) cameras are currently undergoing a major upgrade, with the goals of improving the overall performance of the array and reducing the failure rate of the ageing systems. With the exception of the 960 PMTs, all components inside the camera have been replaced: these include the readout and trigger electronics, the power, ventilation and pneumatic systems and the control and data acquisition software. New designs and technical solutions have been introduced: the readout makes use of the NECTAr analog memory chip, which samples and stores the PMT signals and was developed for the Cherenkov Telescope Array (CTA). The control of all hardware subsystems is carried out by an FPGA coupled to an embedded ARM computer, a modular design which has proven to be very fast and reliable. The new camera software is based on modern C++ libraries such as Apache Thrift, ØMQ and Protocol buffers, offering very good performance, robustness, flexibility and ease of development. The first camera was upgraded in 2015, the other three cameras are foreseen to follow in fall 2016. We describe the design, the performance, the results of the tests and the lessons learned from the first upgraded H.E.S.S. camera.
On-sky tests of a polarization grating for visible astronomy
Author(s):
Maxwell A. Millar-Blanchaer;
Dae-Sik Moon;
James R. Graham;
Michael Williams
Show Abstract
Polarization gratings (PGs) are a type of diffraction grating that take advantage of birefringent liquid crystal polymers to simultaneously act as a polarizing beam splitter and as a spectral dispersive element. Furthermore, PGs are capable of providing high diffraction efficiency (>90%) over a very broad wavelength range. These properties make PGs ideal for spectropolarimetry and/or high throughput, broad wavelength observations for a range of astronomical objects. Here we report on the design and on-sky testing of a prototype spectropolarimeter instrument that employs a PG optimized for operation from 500 nm to 900 nm. The prototype was mounted on a 16-inch telescope at the University of Toronto, where we carried out observations of the polarized twilight sky, a polarized standard star and two spectroscopic standard stars. Using these observations we demonstrate the PG's ability to measure linear polarization fraction and position angle, as well as recover spectra from astronomical objects.
Gemini Instrument Upgrade Program
Author(s):
Ruben Diaz;
Stephen Goodsell;
Scot Kleinman
Show Abstract
The Gemini Observatory* remains committed to keeping its operational instrumentation competitive and serving the needs of its user community. Currently the observatory operates a 4 instruments + 1 AO system at each site. At Gemini North the GMOS-N, GNIRS, NIFS and NIRI instruments are offered supported by the ALTAIR AO system. In the south, GMOS-S, F-2, GPI and GSAOI are offered instrumentation and GeMS is the provided AO System. This paper reviews our strategy to keep our instrumentation suite competitive, examines both our current funded upgrade projects and our potential future enhancements. We summarize the work done and the results so far obtained within the instrument upgrade program.
Commissioning the polarimetric modes of the Robert Stobie spectrograph on the Southern African Large Telescope
Author(s):
S. B. Potter;
Ken Nordsieck;
Encarni Romero-Colmenero;
Steve Crawford;
Petri Vaisanen;
Éric Depagne;
David Buckley;
Anthony Koeslag;
Janus Brink;
Christian Hetlage;
Keith Browne;
Lisa Crause;
Alan Schier;
James Allington
Show Abstract
The Robert Stobie Spectrograph is currently the main workhorse spectroscopic instrument on the Southern African Large Telescope (SALT), which has been undergoing regular scientific operations since 2011. The visible beam of the RSS was designed to perform polarimetry in all of its modes, imaging and grating spectroscopy (with Multi Object Spectroscopy capability) from 3200 to 9000 Å. The polarimetric field of view is 4×8 arcmin. Initial early commissioning of the polarimetric modes was stalled in 2011 because a coupling fluid leak developed in the polarizing beamsplitter after less than a year of operation. As a result, it was decided to redesign the beamsplitter to use a different optical couplant. This was complicated by the unusual thermal expansion properties of the calcite optic, and by the necessity of aligning the individual elements in the beamsplitter mosaic (RSS is the first instrument to use a mosaic beamsplitter). Laboratory work selected a new couplant: a gel, Nye 451. Testing was completed with satisfactory results on a "sacrificial" calcite prism with the same geometry as an actual mosaic element. A successful assembly was performed and the beamsplitter was re-installed in SALT in mid-2015. We describe results from the renewed commissioning efforts to characterize polarimetry from SALT and include some early performance verification science.
Data reductions and data quality for the high resolution spectrograph on the Southern African Large Telescope
Author(s):
S. M. Crawford;
Lisa Crause;
Éric Depagne;
Krystian Ilkiewicz;
Anja Schroeder;
Rudolph Kuhn;
Christian Hettlage;
Encarni Romero Colmenaro;
Alexei Kniazev;
Petri Väisänen
Show Abstract
The High Resolution Spectrograph (HRS) on the Southern African Large Telescope (SALT) is a dual beam, fiber-fed echelle spectrograph providing high resolution capabilities to the SALT observing community. We describe the available data reduction tools and the procedures put in place for regular monitoring of the data quality from the spectrograph. Data reductions are carried out through the pyhrs package. The data characteristics and instrument stability are reported as part of the SALT Dashboard to help monitor the performance of the instrument.
CCD system upgrading of the Kyoto3DII and integral field spectroscopic observation with the new system
Author(s):
Kazuma Mitsuda;
Yasuhito Hashiba;
Yosuke Minowa;
Yutaka Hayano;
Hajime Sugai;
Atsushi Shimono;
Kazuya Matsubayashi;
Takashi Hattori;
Yukiko Kamata;
Shinobu Ozaki;
Mamoru Doi;
Shigeyuki Sako
Show Abstract
The Kyoto Tridimensional Spectrograph II (Kyoto 3DII) is an optical integral field spectrograph mounted on the Subaru telescope as a PI-type instrument. Used with AO188, Kyoto 3DII provides us unique opportunities of optical Integral Field Spectroscopy (IFS) with adaptive optics (AO). While AO works better in redder wavelength regions, quantum efficiency of the previous CCD was low there with optimization for a wider wavelength coverage. To optimize Kyoto 3DII to AO observations, we have newly installed the red-sensitive Hamamatsu fully depleted CCD, which enhances the system efficiency by a factor of ~2 in the red wavelength range. Fringes are dramatically reduced, and the readout noise drops to 3:2-3:4e- about two times smaller than previous, due to refrigerator and readout system. With these improvements, we carried out engineering and scientific observations in September 2015, February and March 2016. We measured the system efficiency using a standard star, and confirmed the successful improvement of the system efficiency. We observed galactic nuclei of nearby galaxies in the Natural Guide Star (NGS) and the Laser Guide Star (LGS) modes. We found the spatial resolution of ~0.1′′ FWHM using a 9.5-magnitude NGS, and ~0.2 - 0:4′′ in LGS mode. Together with the AO resolution, improved efficiency opens a new window for Kyoto 3DII to carry out high resolution optical IFS targeting faint objects such as high-redshift galaxies as well as faint lines such as [OI] λ6300° A and absorption lines of nearby objects.
A new Cassegrain calibration lamp unit for the Blanco Telescope
Author(s):
S. D. Points;
D. J. James;
R. Tighe;
A. Montané;
N. David;
M. Martínez
Show Abstract
The f/8 RC-Cassegrain Focus of the Blanco Telescope at Cerro Tololo Inter-American Observatory, hosts two new instruments: COSMOS, a multi-object spectrograph in the visible wavelength range (350 – 1030nm), and ARCoIRIS, a NIR cross-dispersed spectrograph featuring 6 spectral orders spanning 0.8 – 2.45μm. Here we describe a calibration lamp unit designed to deliver the required illumination at the telescope focal plane for both instruments. These requirements are: (1) an f/8 beam of light covering a spot of 92mm diameter (or 10 arcmin) for a wavelength range of 0.35μm through 2.5μm and (2) no saturation of flat-field calibrations for the minimal exposure times permitted by each instrument, and (3) few saturated spectral lines when using the wavelength calibration lamps for the instruments. To meet these requirements this unit contains an adjustable quartz halogen lamp for flat-field calibrations, and one hollow cathode lamp and four penray lamps for wavelength calibrations. The wavelength calibration lamps are selected to provide optimal spectral coverage for the instrument mounted and can be used individually or in sets. The device designed is based on an 8-inch diameter integrating sphere, the output of which is optimized to match the f/8 calibration input delivery system which is a refractive system based on fused-silica lenses. We describe the optical design, the opto-mechanical design, the electronic control and give results of the performance of the system.
Commissioning and first observations with Wide FastCam at the Telescopio Carlos Sánchez
Author(s):
Sergio Velasco;
Urtats Etxegarai;
Alejandro Oscoz;
Roberto L. López;
Marta Puga;
Gaizka Murga;
Antonio Pérez-Garrido;
Enric Pallé;
Davide Ricci;
Ismael Ayuso;
Mónica Hernández-Sánchez;
Nicola Truant
Show Abstract
The FastCam instrument platform, jointly developed by the IAC and the UPCT, allows, in real-time, acquisition, selection and storage of images with a resolution that reaches the diffraction limit of medium-sized telescopes. FastCam incorporates a specially designed software package to analyse series of tens of thousands of images in parallel with the data acquisition at the telescope. Wide FastCam is a new instrument that, using the same software for data acquisition, does not look for lucky imaging but fast observations in a much larger field of view. Here we describe the commissioning process and first observations with Wide FastCam at the Telescopio Carlos Sanchez (TCS) in the Observatorio del Teide.
Damage and removal of the coating on the first lens of the MegaCam wide-field corrector
Author(s):
Gregory Barrick;
Tom Benedict;
Derrick Salmon
Show Abstract
The coating on the exposed surface of the 810 mm diameter first element of the MegaCam wide-field corrector at the Canada-France-Hawaii Telescope (CFHT) was found to be degraded in the fall of 2014. An investigation showed that the coating was, in fact, damaged over a large part of the exposed surface and was causing major scattering, severely degrading the performance of the instrument. The coating was subsequently removed from the lens by CFHT, restoring the majority of the instrument performance. The investigation of the degradation and the procedure used to remove the coating will be described in this paper.
Upgrade of the detector in the integral field spectrograph OSIRIS at the W. M. Keck Observatory
Author(s):
Anna Boehle;
James E. Larkin;
Sean M. Adkins;
Theodore Aliado;
Michael P. Fitzgerald;
Christopher A. Johnson;
James E. Lyke;
Kenneth G. Magnone;
Ji Man Sohn;
Eric Wang;
Jason L. Weiss
Show Abstract
We present the results of the upgrade of the spectrograph detector in the integral field spectrograph, OSIRIS. OSIRIS is a near-infrared (1 to 2.5 microns) integral field spectrograph on the Keck I telescope. This instrument produces up to 3,000 spectra simultaneously over a contiguous rectangular field of view with a spectral resolution of ~3,800. OSIRIS works with the Keck Adaptive Optics system to achieve diffraction-limited spatial resolution and has four plate scales ranging from 0.02 to 0.10 arcseconds. At first light in 2005, the spectrograph portion of the instrument was equipped with a Rockwell Hawaii-2 detector. We have now upgraded this to a Teledyne Hawaii-2RG (H2RG) with lower read noise, lower dark current, and higher quantum efficiency. In addition to the upgraded detector, we also mounted the detector head on a linear stage, allowing the position of the detector to be accurately adjusted along the optical path when the instrument is at cryogenic temperatures (~80 K). This reduced the number of cool downs required to put the detector image plane at the spectrograph camera focus and adjust any residual tip/tilt of the detector image plane. We present the results of commissioning the new detector and the improved sensitivities of the OSIRIS instrument due to this upgrade.
Optical design of the slit-viewing camera for the NIRSPEC upgrade
Author(s):
Emily C. Martin;
Michael P. Fitzgerald;
Ian S. McLean;
Evan Kress;
Eric Wang
Show Abstract
NIRSPEC is a 1-5 μm high- and medium-resolution echelle spectrograph for the Keck II telescope, delivered in 1999 by the UCLA Infrared Laboratory (PI: Ian McLean). The instrument will be upgraded to replace detectors and electronics in the spectrograph (SPEC) and slit-viewing camera (SCAM). The existing SCAM design is limited to the 1-2.5 μm regime and optimized for the PICNIC 256x256 40-μm-pixel array. The upgrade of the SCAM to a Teledyne H1RG 1024x1024 18-μm-pixel array will allow imaging of the slit from 1-5 μm, increasing observing efficiency in the L and M bands. The extension of SCAM’s wavelength coverage requires re-optimization of its optical design. We present a proof-of-concept optical design of the new SCAM, optimized for a replacement detector. We discuss lens choices, design constraints, and the addition of blocking filters to mitigate saturation issues related to the high background levels in the thermal infrared.
On-sky commissioning of Hamamatsu CCDs in GMOS-S
Author(s):
German Gimeno;
Katherine Roth;
Kristin Chiboucas;
Pascale Hibon;
Luc Boucher;
John White;
Matthew Rippa;
Kathleen Labrie;
James Turner;
Kevin Hanna;
Manuel Lazo;
Gabriel Pérez;
Rolando Rogers;
Roberto Rojas;
Vinicius Placco;
Richard Murowinski
Show Abstract
GMOS-S has been recently upgraded with Hamamatsu deep depletion CCDs, replacing the original EEV detector array. The new CCDs have superior quantum efficiency (QE) at wavelengths longer than 680nm, with significant sensitivity extending beyond 1 micron. Furthermore, the fringing level in GMOS-S data is now much lower due to the much thicker CCDs, additionally improving delivered sensitivity above that afforded by quantum efficiency alone. Soon after the Hamamatsu CCDs were installed in June 2014, some issues were noticed that impacted the ability to execute some science programs. In October 2015 the ARC controller electronics were upgraded and a cable was replaced, and since November 2015 GMOS-S has again been taking science data with the Hamamatsu detectors with no sign of the previous limitations. We present the results of the GMOS-S on-sky commissioning of the Hamamatsu detector array, and provide an update on the status of the GMOS-N portion of the project.
Easy mounting interface for compact instruments at TNG
Author(s):
Adriano Ghedina;
A. Luis Riverol Rodriguez
Show Abstract
The Telescopio Nazionale Galileo (TNG) is able to offer an F/11 Nasmyth focal station with an easy mount for small devices or compact instruments. The slit masks at the focal plane of the LRS spectrograph can be removed in few minutes from the selector stage. A FoV of ~9x9arcmin2 is available and a small instrument can be mounted instead of the slit on a mechanical interface of 240x125mm. The size of the instrument along the optical axis is limited by the support of the collimation lens of the spectrograph. This solution has already been used for small devices like a CCD camera or a SH sensor and a compact Hamamatsu photometer. Furthermore from 2016 it will host the folding optical relay for the GIARPS Instrument. This interface is an opportunity to test new instruments, prototypes or demonstrators in a not invasive or time consuming manner at a 4m class telescope.
A method for reducing atmospheric noise without chopping for ground-based mid-infrared observations
Author(s):
Tomohiko Nakamura;
Takashi Miyata;
Shigeyuki Sako;
Takafumi Kamizuka;
Kentaro Asano;
Mizuho Uchiyama;
Kazushi Okada
Show Abstract
We introduce a new method named as “weighted average method" to reduce atmospheric noise on the images in ground based mid-infrared observations. The main idea of this method is to find a sky frame corresponded to an object frame by superposition of several sky frames, instead of the conventional chop-and-nod observation technique. This is very useful not only for improving the observing efficiency but also for taking images of extended objects larger than the chopping throw. This method is also valid for reducing data taken by the chopping with insufficient frequency. In this paper we will report the details of the weighted average method and demonstrate its performance against practical observing data.
SOFIA's secondary mirror assembly: in-flight performance and control approach
Author(s):
Andreas Reinacher;
Yannick Lammen;
Hans-Peter Roeser
Show Abstract
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5m infrared telescope built into a Boeing 747 SP. In 2014 SOFIA reached its Full Operational Capability milestone and nowadays takes off about three times a week to observe the infrared sky from altitudes above most of the atmosphere’s water vapor content. An actively controlled 352mm SiC secondary mirror is used for infrared chopping with peak-to-peak amplitudes of up to 10 arcmin and chop frequencies of up to 20Hz and also as actuator for fast pointing corrections. The Swiss-made Secondary Mirror Mechanism (SMM) is a complex, highly integrated and compact flexure based mechanism that has been performing with remarkable reliability during recent years. Above mentioned capabilities are provided by the Tilt Chopper Mechanism (TCM) which is one of the two stages of the SMM. In addition the SMM is also used to establish a collimated telescope and to adjust the telescope focus depending on the structure’s temperature which ranges from about 40°C at takeoff in Palmdale, CA to about −40◦C in the stratosphere. This is achieved with the Focus Center Mechanism (FCM) which is the base stage of the SMM on which the TCM is situated. Initially the TCM was affected by strong vibrations at about 300 Hz which led to unacceptable image smearing. After some adjustments to the PID-type controller it was finally decided to develop a completely new control algorithm in state space. This pole placement controller matches the closed loop system poles to those of a Bessel filter with a corner frequency of 120 Hz for optimal square wave behavior. To reduce noise present on the position and current sensors and to estimate the velocity a static gain Kalman Filter was designed and implemented. A system inherent delay is incorporated in the Kalman filter design and measures were applied to counteract the actuators’ hysteresis. For better performance over the full operational temperature range and to represent an amplitude dependent non-linearity the underlying model of the Kalman filter adapts in real-time to those two parameters. This highly specialized controller was developed over the course of years and only the final design is introduced here. The main intention of this contribution is to present the currently achieved performance of the SOFIA chopper over the full amplitude, frequency, and temperature range. Therefore a range of data gathered during in-flight tests aboard SOFIA is displayed and explained. The SMM’s three main performance parameters are the transition time between two chop positions, the stability of the Secondary Mirror when exposed to the low pressures, low temperatures, aerodynamic, and aeroacoustic excitations present when the SOFIA observatory operates in the stratosphere at speeds of up to 850 km/h, and finally the closed-loop bandwidth available for fast pointing corrections.
Development of the FPI+ as facility science instrument for SOFIA cycle four observations
Author(s):
Enrico Pfüller;
Manuel Wiedemann;
Jürgen Wolf;
Alfred Krabbe
Show Abstract
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a heavily modified Boeing 747SP aircraft, accommodating a 2.5m infrared telescope. This airborne observation platform takes astronomers to flight altitudes of up to 13.7 km (45,000ft) and therefore allows an unobstructed view of the infrared universe at wavelengths between 0.3 m and 1600 m. SOFIA is currently completing its fourth cycle of observations and utilizes eight different imaging and spectroscopic science instruments. New instruments for SOFIAs cycle 4 observations are the High-resolution Airborne Wideband Camera-plus (HAWC+) and the Focal Plane Imager (FPI+). The latter is an integral part of the telescope assembly and is used on every SOFIA flight to ensure precise tracking on the desired targets. The FPI+ is used as a visual-light photometer in its role as facility science instrument. Since the upgrade of the FPI camera and electronics in 2013, it uses a thermo-electrically cooled science grade EM-CCD sensor inside a commercial-off-the-shelf Andor camera. The back-illuminated sensor has a peak quantum efficiency of 95% and the dark current is as low as 0.01 e-/pix/sec. With this new hardware the telescope has successfully tracked on 16th magnitude stars and thus the sky coverage, e.g. the area of sky that has suitable tracking stars, has increased to 99%. Before its use as an integrated tracking imager, the same type of camera has been used as a standalone diagnostic tool to analyze the telescope pointing stability at frequencies up to 200 Hz (imaging with 400 fps). These measurements help to improve the telescope pointing control algorithms and therefore reduce the image jitter in the focal plane. Science instruments benefit from this improvement with smaller image sizes for longer exposure times. The FPI has also been used to support astronomical observations like stellar occultations by the dwarf planet Pluto and a number of exoplanet transits. Especially the observation of the occultation events benefits from the high camera sensitivity, fast readout capability and the low read noise and it was possible to achieve high time resolution on the photometric light curves. This paper will give an overview of the development from the standalone diagnostic camera to the upgraded guiding/tracking camera, fully integrated into the telescope, while still offering the diagnostic capabilities and finally to the use as a facility science instrument on SOFIA.
Avalanche photo diodes in the observatory environment: lucky imaging at 1-2.5 microns
Author(s):
A. Vaccarella;
R. Sharp;
M. Ellis;
S. Singh;
G. Bloxham;
A. Bouchez;
R. Conan;
R. Boz;
D. Bundy;
J. Davies;
B. Espeland;
J. Hart;
N. Herrald;
M. Ireland;
G. Jacoby;
J. Nielsen;
C. Vest;
P. Young;
B. Fordham;
A. Zovaro
Show Abstract
The recent availability of large format near-infrared detectors with sub-election readout noise is revolutionizing our approach to wavefront sensing for adaptive optics. However, as with all near-infrared detector technologies, challenges exist in moving from the comfort of the laboratory test-bench into the harsh reality of the observatory environment. As part of the broader adaptive optics program for the GMT, we are developing a near-infrared Lucky Imaging camera for operational deployment at the ANU 2.3 m telescope at Siding Spring Observatory. The system provides an ideal test-bed for the rapidly evolving Selex/SAPHIRA eAPD technology while providing scientific imaging at angular resolution rivalling the Hubble Space Telescope at wavelengths λ = 1.3-2.5 μm.
Final integration and alignment of LINC-NIRVANA
Author(s):
Javier Moreno-Ventas ;
Peter Bizenberger;
Thomas Bertram;
Kalyan K. Radhakrishnan;
Frank Kittmann;
Harald Baumeister;
Luca Marafatto;
Lars Mohr;
Tom Herbst
Show Abstract
The LBT (Large Binocular Telescope), located at about 3200m on Mount Graham (Tucson, Arizona) is an innovative project undertaken by institutions from Europe and USA. LINC-NIRVANA is an instrument which provides MCAO (Multi-Conjugate Adaptive Optics) and interferometry, combining the light from the two 8.4m telescopes coherently. This configuration offers 23m-baseline optical resolution and the sensitivity of a 12m mirror, with a 2 arc-minute diffraction limited field of view. The integration, alignment and testing of such a big instrument requires a well-organized choreography and AIV planning which has been developed in a hierarchical way. The instrument is divided in largely independent systems, and all of them consist of various subsystems. Every subsystem integration ends with a verification test and an acceptance procedure. When a certain number of systems are finished and accepted, the instrument AIV phase starts. This hierarchical approach allows testing at early stages with simple setups. The philosophy is to have internally aligned subsystems to be integrated in the instrument optical path, and extrapolate to finally align the instrument to the Gregorian bent foci of the telescope. The alignment plan was successfully executed in Heidelberg at MPIA facilities, and now the instrument is being re-integrated at the LBT over a series of 11 campaigns along the year 2016. After its commissioning, the instrument will offer MCAO sensing with the LBT telescope. The interferometric mode will be implemented in a future update of the instrument. This paper focuses on the alignment done in the clean room at the LBT facilities for the collimator, camera, and High-layer Wavefront Sensor (HWS) during March and April 2016. It also summarizes the previous work done in preparation for shipping and arrival of the instrument to the telescope. Results are presented for every step, and a final section outlines the future work to be done in next runs until its final commissioning.
SPHERE IRDIS and IFS astrometric strategy and calibration
Author(s):
Anne-Lise Maire;
Maud Langlois;
Kjetil Dohlen;
Anne-Marie Lagrange;
Raffaele Gratton;
Gaël Chauvin;
Silvano Desidera;
Julien H. Girard;
Julien Milli;
Arthur Vigan;
Gerard Zins;
Philippe Delorme;
Jean-Luc Beuzit;
Riccardo U. Claudi;
Markus Feldt;
David Mouillet;
Pascal Puget;
Massimo Turatto;
François Wildi
Show Abstract
We present the current results of the astrometric characterization of the VLT planet finder SPHERE over 2 years of on-sky operations. We first describe the criteria for the selection of the astrometric fields used for calibrating the science data: binaries, multiple systems, and stellar clusters. The analysis includes measurements of the pixel scale and the position angle with respect to the North for both near-infrared subsystems, the camera IRDIS and the integral field spectrometer IFS, as well as the distortion for the IRDIS camera. The IRDIS distortion is shown to be dominated by an anamorphism of 0.60±0.02% between the horizontal and vertical directions of the detector, i.e. 6 mas at 1 arcsec. The anamorphism is produced by the cylindrical mirrors in the common path structure hence common to all three SPHERE science subsystems (IRDIS, IFS, and ZIMPOL), except for the relative orientation of their field of view. The current estimates of the pixel scale and North angle for IRDIS are 12.255±0.009 milliarcseconds/pixel for H2 coronagraphic images and -1.70±0.08°. Analyses of the IFS data indicate a pixel scale of 7.46±0.02 milliarcseconds/pixel and a North angle of -102.18±0.13°. We finally discuss plans for providing astrometric calibration to the SPHERE users outside the instrument consortium.
Modeling the transmission and thermal emission in a pupil image behind the Keck II adaptive optics system
Author(s):
Pauline Arriaga;
Michael P. Fitzgerald;
James E. Lyke;
Randall D. Campbell;
Peter L. Wizinowich;
Sean M. Adkins;
Keith Y. Matthews
Show Abstract
The design and performance of astronomical instruments depend critically on the total system throughput as well as the background emission from the sky and instrumental sources. In designing a pupil stop for background- limited imaging, one seeks to balance throughput and background rejection to optimize measurement signal-to-noise ratios. Many sources affect transmission and emission in infrared imaging behind the Keck Observatory’s adaptive optics systems, such as telescope segments, segment gaps, secondary support structure, and AO bench optics. Here we describe an experiment, using the pupil-viewing mode of NIRC2, to image the pupil plane as a function of wavelength. We are developing an empirical model of throughput and background emission as a function of position in the pupil plane. This model will be used in part to inform the optimal design of cold pupils in future instruments, such as the new imaging camera for OSIRIS.
GPI observational calibrations XIV: polarimetric contrasts and new data reduction techniques
Author(s):
Maxwell A. Millar-Blanchaer;
Marshall D. Perrin;
Li-Wei Hung;
Michael P. Fitzgerald;
Jason J. Wang;
Jeffrey Chilcote;
James R. Graham;
Sebastian Bruzzone;
Paul G. Kalas
Show Abstract
The Gemini Planet Imager (GPI) has been designed for the direct detection and characterization of exoplanets and circumstellar disks. GPI is equipped with a dual channel polarimetry mode designed to take advantage of the inherently polarized light scattered off circumstellar material to further suppress the residual seeing haloleft uncorrected by the adaptive optics. We explore how recent advances in data reduction techniques reduce systematics and improve the achievable contrast in polarimetry mode. In particular, we consider different flux extraction techniques when constructing datacubes from raw data, division by a polarized at-field and a method for subtracting instrumental polarization. Using observations of unpolarized standard stars we find that GPI's instrumental polarization is consistent with being wavelength independent within our errors. In addition, we provide polarimetry contrast curves that demonstrate typical performance throughout the GPIES campaign.
Gemini Planet Imager observational calibrations XI: pipeline improvements and enhanced calibrations after two years on sky
Author(s):
Marshall D. Perrin;
Patrick Ingraham;
Katherine B. Follette;
Jérôme Maire;
Jason J. Wang;
Dmitry Savransky;
Pauline Arriaga;
Vanessa P. Bailey;
Sebastian Bruzzone;
Jeffrey K. Chilcote;
Robert J. De Rosa;
Zachary H. Draper;
Michael P. Fitzgerald;
Alexandra Z. Greenbaum;
Li-Wei Hung;
Quinn Konopacky;
Bruce Macintosh;
Franck Marchis;
Christian Marois;
Maxwell A. Millar-Blanchaer;
Eric Nielsen;
Abhijith Rajan;
Julien Rameau;
Fredrik T. Rantakyro;
Jean-Baptiste Ruffio;
Kimberly Ward-Duong;
Schuyler G. Wolff;
Joseph Zalesky
Show Abstract
The Gemini Planet Imager has been successfully obtaining images and spectra of exoplanets, brown dwarfs, and debris and protoplanetary circumstellar disks using its integral field spectrograph and polarimeter. GPI observations are transformed from raw data into high-quality astrometrically and photometrically calibrated datacubes using the GPI Data Reduction Pipeline, an open-source software framework continuously developed by our team and available to the community. It uses a flexible system of reduction recipes composed of individual primitive steps, allowing substantial customization of processing depending upon science goals. This paper provides a broad overview of the GPI pipeline, summarizes key lessons learned, and describes improved calibration methods and new capabilities available in the latest version. Enhanced automation better supports observations at the telescope with streamlined and rapid data processing, for instance through real-time assessments of contrast performance and more automated calibration file processing. We have also incorporated the GPI Data Reduction Pipeline as one component in a larger automated data system to support the GPI Exoplanet Survey campaign, while retaining its flexibility and stand-alone capabilities to support the broader GPI observer community. Several accompanying papers describe in more detail specific aspects of the calibration of GPI data in both spectral and polarimetric modes.
Gemini planet imager observational calibration XIII: wavelength calibration improvements, stability, and nonlinearity
Author(s):
Schuyler G. Wolff;
Kimberly Ward-Duong;
Joe Zalesky;
Alex Z. Greenbaum;
Marshall D. Perrin;
James Graham
Show Abstract
We present improvements to the wavelength calibration for the lenslet-based Integral Field Spectrograph (IFS), that serves as the science instrument for the Gemini Planet Imager (GPI). The GPI IFS features a 2.7”×2.7” field of view and a 190 x 190 lenslet array (14.1 mas/lenslet) with spectral resolving power ranging from R ~ 35 to 78. A unique wavelength solution is determined for each lenslet characterized by a two-dimensional position, an n-dimensional polynomial describing the spectral dispersion, and the rotation of the spectrum with respect to the detector axis. We investigate the non-linearity of the spectral dispersion across all Y, J, H, and K bands through both on-sky arc lamp images and simulated IFS images using a model of the optical path. Additionally, the 10-hole non-redundant masking mode on GPI provides an alternative measure of wavelength dispersion within a datacube by cross-correlating reference PSFs with science images. This approach can be used to confirm deviations from linear dispersion in the reduced datacubes. We find that the inclusion of a quadratic term provides a factor of 10 improvement in wavelength solution accuracy over the linear solution and is necessary to achieve uncertainties of a few hundredths of a pixel in J band to a few thousands of a pixel in the K bands. This corresponds to a wavelength uncertainty of ~ 0.2 nm across all filters.
Design of the ERIS calibration unit
Author(s):
Mauro Dolci;
Angelo Valentini;
Gianluca Di Rico;
Simone Esposito;
Debora Ferruzzi;
Armando Riccardi;
Paolo Spanò;
Jacopo Antichi
Show Abstract
The Enhanced Resolution Imager and Spectrograph (ERIS) is a new-generation instrument for the Cassegrain focus of the ESO UT4/VLT, aimed at performing AO-assisted imaging and medium resolution spectroscopy in the 1-5 micron wavelength range. ERIS consists of the 1-5 micron imaging camera NIX, the 1-2.5 micron integral field spectrograph SPIFFIER (a modified version of SPIFFI, currently operating on SINFONI), the AO module and the internal Calibration Unit (ERIS CU). The purpose of this unit is to provide facilities to calibrate the scientific instruments in the 1-2.5 micron and to perform troubleshooting and periodic maintenance tests of the AO module (e.g. NGS and LGS WFS internal calibrations and functionalities, ERIS differential flexures) in the 0.5 – 1 μm range. The ERIS CU must therefore be designed in order to provide, over the full 0.5 – 2.5 μm range, the following capabilities: 1) illumination of both the telescope focal plane and the telescope pupil with a high-degree of uniformity; 2) artificial point-like and extended sources onto the telescope focal plane, with high accuracy in both positioning and FWHM; 3) wavelength calibration; 4) high stability of these characteristics. In this paper the design of the ERIS CU, and the solutions adopted to fulfill all these requirements, is described. The ERIS CU construction is foreseen to start at the end of 2016.
Gemini planet imager observational calibration XII: photometric calibration in the polarimetry mode
Author(s):
Li-Wei Hung;
Sebastian Bruzzone;
Maxwell A. Millar-Blanchaer;
Jason J. Wang;
Pauline Arriaga;
Stanimir Metchev;
Michael P. Fitzgerald;
Anand Sivaramakrishnan;
Marshall D. Perrin
Show Abstract
The Gemini Planet Imager (GPI) is a high-contrast instrument specially designed for direct imaging and spectroscopy of exoplanets and debris disks. GPI can also operate as a dual-channel integral field polarimeter. The instrument primarily operates in a coronagraphic mode which poses an obstacle for traditional photometric calibrations since the majority of on-axis starlight is blocked. To enable accurate photometry relative to the occulted central star, a diffractive grid in a pupil plane is used to create a set of faint copies, named satellite spots, of the occulted star at specified locations and relative intensities in the field of view. We describe the method we developed to perform the photometric calibration of coronagraphic observations in polarimetry mode using these fiducial satellite spots. With the currently available data, we constrain the calibration uncertainty to be <13%, but the actual calibration uncertainty is likely to be lower. We develop the associated calibration scripts in the GPI Data Reduction Pipeline, which is available to the public. For testing, we use it to photometrically calibrate the HD 19467 B and β Pic b data sets taken in the H-band polarimetry mode. We measure the calibrated flux of HD 19467 B and β Pic b to be 0:078±0:011 mJy and 4:87±0:73 mJy, both agreeing with other measurements found in the literature. Finally, we explore an alternative method which performs the calibration by scaling the photometry in polarimetry mode to the photometrically calibrated response in spectroscopy mode. By comparing the reduced observations in raw units, we find that observations in polarimetry mode are 1:03 0:01 brighter than those in spectroscopy mode.
An ADC for the SAM on the SOAR Telescope
Author(s):
Roberto Tighe;
Andrei Tokovinin;
Patricio Schurter;
Manuel Martínez;
Rolando Cantarutti
Show Abstract
SAM (Soar Adaptive-optics Module), the SOAR (Southern Observatory for Astrophysical Research) GLAO facility is in service since 2011, with a UV, 355nm Laser Guide Star (LGS). The atmospheric wavefront error is therefore measured at 355nm and the star images are corrected in the visible range (BVRI bands). An ADC is required for High Resolution imaging at low telescope elevation, especially at shorter wavelengths of the visible spectrum. The ADC is based on 80mm diameter rotating prisms. This compact unit, fully automated, can be inserted or removed from the tightly constrained SAM collimated beam space-envelope, it adjusts to the parallactic angle and corrects the atmospheric dispersion. Here we present the optical and opto-mechanical design, the control design, the operational strategy and performance results obtained from extensive use in on-sky HR Speckle Imaging.
Infrared photometry with 'wall-eyed' pointing at the Large Binocular Telescope
Author(s):
Eckhart Spalding;
Andrew Skemer;
Philip M. Hinz;
John M. Hill
Show Abstract
The brightness and variability of the atmosphere in the thermal infrared poses obstacles to precision photometry measurements. The need to remove atmospheric effects calls for the use of a comparison star, but it is usually impossible to fit both science and comparison targets on current long-wavelength (>2 μm) detectors. We present a new pointing mode at the Large Binocular Telescope, which has twin 8.4-m primary mirrors that can be pointed up to ~2 arcminutes apart and allow the placement of both targets on a small-field infrared detector. We present an observation of the primary transit of an exoplanet in front of its host star, and use it to provide preliminary constraints on the attainable photometric precision.
SPHERE on-sky performance compared with budget predictions
Author(s):
Kjetil Dohlen;
Arthur Vigan;
David Mouillet;
François Wildi;
Jean-François Sauvage;
Thierry Fusco;
Jean-Luc Beuzit;
Pascal Puget;
David Le Mignant;
Ronald Roelfsema;
Johan Pragt;
Hans Martin Schmid;
Raffaele Gratton;
Dino Mesa;
Riccardo Claudi;
Maud Langlois;
Anne Costille;
Emmanuel Hugot;
Jared O'Neil;
Juan Carlos Guerra;
Mamadou N'Diaye;
Julien Girard;
Dimitri Mawet;
Gerard Zins
Show Abstract
The SPHERE (spectro-photometric exoplanet research) extreme-AO planet hunter saw first light at the VLT observatory on Mount Paranal in May 2014 after ten years of development. Great efforts were put into modelling its performance, particularly in terms of achievable contrast, and to budgeting instrumental features such as wave front errors and optical transmission to each of the instrument’s three focal planes, the near infrared dual imaging camera IRDIS, the near infrared integral field spectrograph IFS and the visible polarimetric camera ZIMPOL. In this paper we aim at comparing predicted performance with measured performance. In addition to comparing on-sky contrast curves and calibrated transmission measurements, we also compare the PSD-based wave front error budget with in-situ wave front maps obtained thanks to a Zernike phase mask, ZELDA, implemented in the infrared coronagraph wheel. One of the most critical elements of the SPHERE system is its high-order deformable mirror, a prototype 40x40 actuator piezo stack design developed in parallel with the instrument itself. The development was a success, as witnessed by the instrument performance, in spite of some bad surprises discovered on the way. The devastating effects of operating without taking properly into account the loss of several actuators and the thermally and temporally induced variations in the DM shape will be analysed, and the actions taken to mitigate these defects through the introduction of specially designed Lyot stops and activation of one of the mirrors in the optical train will be described.
Pushing down with the contrast: scientific performances with SPHERE-IFS
Author(s):
R. Claudi;
J. Antichi;
A. Baruffolo;
P. Bruno;
E. Cascone;
V. DeCaprio;
M. DePascale;
S. Desidera;
V. D'Orazi;
D. Fantinel;
G. Farisato;
E. Giro;
R. Gratton;
L. Lessio;
A.L. Maire;
D. Mesa;
B. Salasnich;
S. Scuderi;
E. Sissa;
M. Turatto;
A. Zurlo;
JL Beuzit;
A. Boccaletti;
G. Chauvin;
K. Dohlen;
G. Finger;
J. H. Girard;
M. Kasper;
N. Hubin;
M. Langlois;
J. L. Lizon;
D. Mouillet;
P. Puget;
F. Wildi
Show Abstract
The VLT second generation instrument SPHERE (Spectro-Polarimetric High-contrast Exoplanets Research) was commissioned in the Summer of 2014, and offered to the community in the Spring of 2015. SPHERE is a high contrast imager that exploits its three scientific channels in order to observe and discover young warm exoplanets in the glare of their host stars. The three scientific instrument are: ZIMPOL, a polarization analyzer and imager that works in the visible range of wavelength, IRDIS a dual band imager and spectro polarimetric Camera that works in the NIR range up to K band, and IFS, an integral field spectrograph working in the YJH band. Very important is the complementarity between IRDIS and IFS. The former has a larger Field of view (about 12 arcseconds) while the IFS push its examination very close to the central star (FoV ~ 1.7 arcsec). In one year of operational time a lot of very interesting scientific cases were investigated and very nice results were gathered. In this paper we would like to focus the attention on the high quality results and performances obtained with the IFS.
H2RG detector characterization for RIMAS and instrument efficiencies
Author(s):
Vicki L. Toy;
Alexander S. Kutyrev;
John I. Capone;
Thomas Hams;
F. David Robinson;
Gennadiy N. Lotkin;
Sylvain Veilleux;
Samuel H. Moseley;
Neil A. Gehrels;
Stuart N. Vogel
Show Abstract
The Rapid infrared IMAger-Spectrometer (RIMAS) is a near-infrared (NIR) imager and spectrometer that will quickly follow up gamma-ray burst afterglows on the 4.3-meter Discovery Channel Telescope (DCT). RIMAS has two optical arms which allows simultaneous coverage over two bandpasses (YJ and HK) in either imaging or spectroscopy mode. RIMAS utilizes two Teledyne HgCdTe H2RG detectors controlled by Astronomical Research Cameras, Inc. (ARC/Leach) drivers. We report the laboratory characterization of RIMAS's detectors: conversion gain, read noise, linearity, saturation, dynamic range, and dark current. We also present RIMAS's instrument efficiency from atmospheric transmission models and optics data (both telescope and instrument) in all three observing modes.
An optical design of the wide-field imaging and multi-object spectrograph for an Antarctic infrared telescope
Author(s):
Takashi Ichikawa;
Tomokazu Obata
Show Abstract
A design of the wide-field infrared camera (AIRC) for Antarctic 2.5m infrared telescope (AIRT) is presented. The off-axis design provides a 7’.5 ×7’. 5 field of view with 0”.22 pixel-1 in the wavelength range of 1 to 5 μm for the simultaneous three-color bands using cooled optics and three 2048×2048 InSb focal plane arrays. Good image quality is obtained over the entire field of view with practically no chromatic aberration. The image size corresponds to the refraction limited for 2.5 m telescope at 2 μm and longer. To enjoy the stable atmosphere with extremely low perceptible water vapor (PWV), superb seeing quality, and the cadence of the polar winter at Dome Fuji on the Antarctic plateau, the camera will be dedicated to the transit observations of exoplanets. The function of a multi-object spectroscopic mode with low spectra resolution (R~50-100) will be added for the spectroscopic transit observation at 1-5 μm. The spectroscopic capability in the environment of extremely low PWV of Antarctica will be very effective for the study of the existence of water vapor in the atmosphere of super earths.
GravityCam: wide-field, high-resolution imaging and high-speed photometry instrument
Author(s):
Craig MacKay;
Martin Dominik;
Iain Steele
Show Abstract
The limits to the angular resolution achievable with conventional ground-based telescopes are unchanged over 70 years. Atmospheric turbulence limits image quality to typically ~1 arcsec in practice. We have developed a new concept of ground-based imaging instrument called GravityCam capable of delivering significantly sharper images from the ground than is normally possible without adaptive optics. The acquisition of visible images at high speed without significant noise penalty has been made possible by advances in optical and near IR imaging technologies. Images are recorded at high speed and then aligned before combination and can yield a 3-5 fold improvement in image resolution. Very wide survey fields are possible with widefield telescope optics. We describe GravityCam and detail its application to accelerate greatly the rate of detection of Earth size planets by gravitational microlensing. GravityCam will also improve substantially the quality of weak shear studies of dark matter distribution in distant clusters of galaxies. The microlensing survey will also provide a vast dataset for asteroseismology studies. In addition, GravityCam promises to generate a unique data set that will help us understand of the population of the Kuiper belt and possibly the Oort cloud.
Advances in the development of a Mach-Zehnder interferometric Doppler imager for seismology of giant planets
Author(s):
Ivan Gonçalves;
François-Xavier Schmider;
Yves Bresson;
Julien Dejonghe;
Olivier Preis;
Sylvie Robbe-Dubois;
Thierry Appourchaux;
Patrick Boumier;
Jean-Christophe Leclec'h;
Gilles Morinaud;
Patrick Gaulme;
Jason Jackiewicz
Show Abstract
The measurements of radial velocity fields on planets with a Doppler Spectro-Imager allow the study of atmospheric dynamics of giant planets and the detection of their acoustic oscillations. The frequencies of these oscillations lead to the determination of the internal structure by asteroseismology. A new imaging tachometer, based on a Mach-Zehnder interferometer, has been developed to monitor the Doppler shift of solar lines reflected at the surface of the planets. We present the principle of this instrument. A prototype was designed and built, following the specifications of a future space mission. The performance of the prototype, both at the laboratory and on the sky, is presented here.
Design, assembly, and performance of the low-resolution spectrograph 2 integral field unit
Author(s):
Brian L. Vattiat;
Hanshin Lee;
Taylor Chonis;
Gary J. Hill;
Christian Haubitz-Reinke
Show Abstract
The Low Resolution Spectrograph 2 (LRS2) was recently deployed on the Hobby-Eberly Telescope (HET). LRS2 consists of four spectrographic channels, each covering adjacent wavelength bands from 360-1050nm which are fed with a fiber optic integral field unit (IFU). The integral field unit developed for this instrument represents a transformative approach to expanding the wavelength coverage of integral field spectrographs. The unique input feed of the IFU serves two functions; combining the wavelength coverage of two spectrographic channels to one spatial field on sky, and expanding the field of view of each individual fiber to eliminate the interstitial space between fibers on sky. The spectral multiplexing is achieved with dichroic beam splitter and collimator, while the focal reduction is achieved with a pair of micro lens arrays. The optical components required micron scale alignment precision in a compact mechanical package to allow integration on the telescope focal surface. Here we report on the design, assembly, and performance of the IFU.
Development of a prototype of the Tomo-e Gozen wide-field CMOS camera
Author(s):
Shigeyuki Sako;
Ryou Osawa;
Hidenori Takahashi;
Yuki Kikuchi;
Mamoru Doi;
Naoto Kobayashi;
Tsutomu Aoki;
Ko Arimatsu;
Makoto Ichiki;
Shiro Ikeda;
Yoshifusa Ita;
Toshihiro Kasuga;
Hideyo Kawakita;
Mitsuru Kokubo;
Hiroyuki Maehara;
Noriyuki Matsunaga;
Hiroyuki Mito;
Kazuma Mitsuda;
Takashi Miyata;
Kiyoshi Mori;
Yuki Mori;
Mikio Morii;
Tomoki Morokuma;
Kentaro Motohara;
Yoshikazu Nakada;
Kentaro Osawa;
Shin-ichiro Okumura;
Hiroki Onozato;
Yuki Sarugaku;
Mikiya Sato;
Toshikazu Shigeyama;
Takao Soyano;
Masaomi Tanaka;
Yuki Taniguchi;
Ataru Tanikawa;
Ken'ichi Tarusawa;
Nozomu Tominaga;
Tomonori Totani;
Seitaro Urakawa;
Fumihiko Usui;
Junichi Watanabe;
Jumpei Yamaguchi;
Makoto Yoshikawa
Show Abstract
The Tomo-e Gozen is an extremely wide-field optical camera for the Kiso 1.0-m Schmidt telescope. It is capable of taking consecutive frames with a field-of-view of 20 deg2 and a sub-second time-resolution, which are achieved by 84 chips of 2k×1k CMOS sensor. This camera adopts unconventional designs including a lightweight structure, a nonvacuumed and naturally-air cooled system, front-side-illuminated CMOS sensors with microlens arrays, a sensor alignment along a spherical focal plane of the telescope, and massive readout electronics. To develop technical components necessary for the Tomo-e Gozen and confirm a feasibility of its basic design, we have developed a prototype-model (PM) of the Tomo-e Gozen prior to the final-model (FM). The Tomo-e PM is equipped with eight chips of the CMOS sensor arranged in a line along the RA direction, covering a sky area of 2.0 deg2. The maximum frame rate is 2 fps. The total data production rate is 80 MByte sec-1 at 2 fps, corresponding to approximately 3 TByte night-1. After laboratory testing, we have successfully obtained consecutive movie data at 2 fps with the Tomo-e PM in the first commissioning run conducted in the end of 2015.
The Wide Integral Field Infrared Spectrograph (WIFIS): optomechanical design and development
Author(s):
R. Elliot Meyer;
Dae-Sik Moon;
Suresh Sivanandam;
Ke Ma;
Chuck Henderson;
Basil Blank;
Chueh-Yi Chou;
Miranda Jarvis;
Stephen S. Eikenberry
Show Abstract
We present the optomechanical design and development of the Wide Integral Field Infrared Spectrograph (WIFIS). WIFIS will provide an unrivalled integral field size of 20”×50” for a near-infrared (0.9-1.7 μm) integral-field spectrograph at the 2.3-meter Steward Bok telescope. Its main optomechanical system consists of two assemblies: a room-temperature bench housing the majority of the optical components and a cryostat for a field-flattening lens, thermal blocking filter, and detector. Two additional optical subsystems will provide calibration functionality, telescope guiding, and off-axis optical imaging. WIFIS will be a highly competitive instrument for seeing-limited astronomical investigations of the dynamics and chemistry of extended objects in the near-infrared wavebands. WIFIS is expected to be commissioned during the end of 2016 with scientific operations beginning in 2017.
Optical design of a multi-resolution, single-shot spectrograph
Author(s):
François Hénault;
Florence Laurent
Show Abstract
Multi-object or integral field spectrographs today are recognized techniques for achieving simultaneous spectroscopic observations of different or extended sky objects with a high multiplex factor. In this communication is described a complementary approach for realizing similar measurements under different spectral resolutions at the same time. Herein is explained the basic principle of this new type of spectrometer, that is based on the utilization of an optical pupil slicer. An optical design inspired from an already studied instrument is then presented and commented for the sake of illustration. Technical issues about the pupil slicer and diffractive components are also discussed. We finally conclude on the potential advantages and drawbacks of the proposed system.
Developing scanning-slit spectrograph for imaging the Sun
Author(s):
Hemanth Pruthvi;
K. B. Ramesh;
Sajal Kumar Dhara;
B. Ravindra
Show Abstract
For moderate resolution spectroscopy of the Sun, an imaging spectrograph is being developed at Indian Institute of Astrophysics. With this instrument images of the region of interest of the Sun can be obtained with low spatial and moderate spectral resolution. Dopplergrams can also be obtained with the acquired data to get line of sight velocity maps. The instrument is a back-end for a telescope with tracking system i.e. stable image of the Sun is projected onto the focal plane at all times. Modular approach is followed in the design, keeping sections of the instruments fairly independent. Scanning-slit assembly is a module that can linearly move in one direction to sweep the region of interest in the image. Spectrograph assembly consists of another slit, optics and dispersing element along with the detector so that spectral information about spatial locations on the slit can be obtained. This module is designed to obtain Intensity vs. (x,λ) (x is along the slit) and as the scanning-slit is swept along the y-direction, Intensity vs. (x,y,λ) information is built. The spatial resolution will be seeing limited as there's no correction system. Field of view is 6 arc minute along the slit direction, as the features of interest include sunspots and surrounding region. For testing, a front end system of 100mm clear aperture with f/22.5 is being used. The dispersing element is a reflecting grating with 1200 grooves/mm. For 6563 Å(H-alpha line) spectral resolution is 35 mÅ in second order. Linear dispersion is about 38 mÅ /pixel for the pixel size of 7.5μm, indicating that slit-width limited spectral resolution can be obtained.
Development status of the mid-infrared two-field camera and spectrograph MIMIZUKU for the TAO 6.5-m Telescope
Author(s):
Takafumi Kamizuka;
Takashi Miyata;
Shigeyuki Sako;
Ryou Ohsawa;
Kazushi Okada;
Masahito S. Uchiyama;
Kiyoshi Mori;
Jumpei Yamaguchi;
Kentaro Asano;
Mizuho Uchiyama;
Itsuki Sakon;
Takashi Onaka;
Hirokazu Kataza;
Sunao Hasegawa;
Fumihiko Usui;
Naruhisa Takato;
Tsutomu Aoki;
Mamoru Doi;
Natsuko M. Kato;
Yutaro Kitagawa;
Yutaka Kobayakawa;
Kotaro Kohno;
Masahiro Konishi;
Takeo Minezaki;
Tomoki Morokuma;
Kentaro Motohara;
Hirofumi Ohashi;
Takao Soyano;
Hidenori Takahashi;
Yoichi Tamura;
Toshihiko Tanabé;
Masuo Tanaka;
Ken'ichi Tarusawa;
Yasunori Terao;
Yuzuru Yoshii
Show Abstract
MIMIZUKU is the first-generation mid-infrared instrument for the university of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU provides imaging and spectroscopic monitoring capabilities in a wide wavelength range from 2 to 38 μm, including unique bands like 2.7-μm and 30-μm band. Recently, we decided to add spectroscopic functions, KL-band mode (λ= 2.1-4.0 μm; R =λ/Δλ ~ 210) and 2.7-μm band mode ( λ= 2.4-2.95 μm; R ~ 620), and continuous spectroscopic coverage from 2.1 to 26 μm is realized by this update. Their optical designing is completed, and fabrications of optical elements are ongoing. As recent progress, we also report the completion of the cryogenic system and optics. The cryogenic system has been updated by changing materials and structures of thermal links, and the temperatures of the optical bench and detector mounting stages finally achieved required temperatures. Their stability against instrument attitude is also confirmed through an inclination test. As for the optics, its gold-plated mirrors have been recovered from galvanic corrosion by refabrication and reconstruction. Enough image quality and stability are confirmed by room-temperature tests. MIMIZUKU is intended to be completed in this autumn, and commissioning at the Subaru telescope and scientific operations on the TAO telescope are planned in 2017 and around 2019, respectively. In this paper, these development activities and future prospects of MIMIZUKU are reported.
The SKA low frequency aperture array
Author(s):
J. G. Bij de Vaate;
P. Benthem;
H. Schnetler
Show Abstract
The deployment of the Square Kilometre Array (SKA) [1] starts with a ~10% instrument, phase 1, commencing with construction in 2018. This includes the SKA1-Low, a sparse Aperture Array (AA) covering 50 to at least 350MHz. SKA1-Low will consist of 512 stations, each with 256 antennas creating a total of more than 130.000 antennas. The configuration will be closed packed with a large fraction of the antennas within a 1.7km radius central area and the remaining collecting area situated on three spiral arms, extending to a radius of ~45km.
SAAO's new robotic telescope and WiNCam (Wide-field Nasmyth Camera)
Author(s):
Hannah L. Worters;
James E. O'Connor;
David B. Carter;
Egan Loubser;
Pieter A. Fourie;
Amanda Sickafoose;
Pieter Swanevelder
Show Abstract
The South African Astronomical Observatory (SAAO) is designing and manufacturing a wide-field camera for use on two of its telescopes. The initial concept was of a Prime focus camera for the 74” telescope, an equatorial design made by Grubb Parsons, where it would employ a 61mmx61mm detector to cover a 23 arcmin diameter field of view. However, while in the design phase, SAAO embarked on the process of acquiring a bespoke 1-metre robotic alt-az telescope with a 43 arcmin field of view, which needs a homegrown instrument suite. The Prime focus camera design was thus adapted for use on either telescope, increasing the detector size to 92mmx92mm. Since the camera will be mounted on the Nasmyth port of the new telescope, it was dubbed WiNCam (Wide-field Nasmyth Camera). This paper describes both WiNCam and the new telescope. Producing an instrument that can be swapped between two very different telescopes poses some unique challenges. At the Nasmyth port of the alt-az telescope there is ample circumferential space, while on the 74 inch the available envelope is constrained by the optical footprint of the secondary, if further obscuration is to be avoided. This forces the design into a cylindrical volume of 600mm diameter x 250mm height. The back focal distance is tightly constrained on the new telescope, shoehorning the shutter, filter unit, guider mechanism, a 10mm thick window and a tip/tilt mechanism for the detector into 100mm depth. The iris shutter and filter wheel planned for prime focus could no longer be accommodated. Instead, a compact shutter with a thickness of less than 20mm has been designed in-house, using a sliding curtain mechanism to cover an aperture of 125mmx125mm, while the filter wheel has been replaced with 2 peripheral filter cartridges (6 filters each) and a gripper to move a filter into the beam. We intend using through-vacuum wall PCB technology across the cryostat vacuum interface, instead of traditional hermetic connector-based wiring. This has advantages in terms of space saving and improved performance. Measures are being taken to minimise the risk of damage during an instrument change. The detector is cooled by a Stirling cooler, which can be disconnected from the cooler unit without risking damage. Each telescope has a dedicated cooler unit into which the coolant hoses of WiNCam will plug. To overcome an inherent drawback of Stirling coolers, an active vibration damper is incorporated. During an instrument change, the autoguider remains on the telescope, and the filter magazines, shutter and detector package are removed as a single unit. The new alt-az telescope, manufactured by APM-Telescopes, is a 1-metre f/8 Ritchey-Chrétien with optics by LOMO. The field flattening optics were designed by Darragh O'Donoghue to have high UV throughput and uniform encircled energy over the 100mm diameter field. WiNCam will be mounted on one Nasmyth port, with the second port available for SHOC (Sutherland High-speed Optical Camera) and guest instrumentation. The telescope will be located in Sutherland, where an existing dome is being extensively renovated to accommodate it. Commissioning is planned for the second half of 2016.
Requirement analysis for a modular low resolution spectrograph
Author(s):
A. S. Piascik;
I. A. Steele
Show Abstract
The utility of a high-throughput, low resolution, optical long-slit spectrograph has been demonstrated with the recent deployment of the SPRAT and LOTUS spectrographs on the 2.0m Liverpool Telescope. In this paper we briefly explore some example science use cases for a more generic spectrograph. Our eventual aim is to a produce an adaptable and compact modular instrument design suitable for general deployment to other robotic or manual 1.5 - 3.0m class telescopes. We find that the wide variety of science goals mean that a single design may not be appropriate, however by developing a common optical/mechanical core to which standard optical elements are added we may be able to accommodate them.
OCTOCAM: a fast multi-channel imager and spectrograph proposed for the Gemini Observatory
Author(s):
A. de Ugarte Postigo;
P. Roming;
C. C. Thöne;
A. J. van der Horst;
S. Pope;
M. L. García Vargas;
E. Sánchez-Blanco;
M. Maldonado Medina;
R. Content;
F. Snik;
R. Killough;
G. Winters;
K. Persson;
S. Jeffers;
A. Riva;
A. Bianco;
A. Zanutta
Show Abstract
OCTOCAM has been proposed to the Gemini Observatory as a workhorse imager and spectrograph that will fulfill the needs of a large number of research areas in the 2020s. It is based on the use of high-efficiency dichroics to divide the incoming light in eight different channels, four optical and four infrared, each optimized for its wavelength range. In its imaging mode, it will observe a field of 3'x3' simultaneously in g, r, i, z, Y, J, H, and KS bands. It will obtain long-slit spectroscopy covering the range from 3700 to 23500 Å with a resolution of 4000 and a slit length of 3 arcminutes. To avoid slit losses, the instrument it will be equipped with an atmospheric dispersion corrector for the complete spectral range. Thanks to the use of state of the art detectors, OCTOCAM will allow high time-resolution observations and will have negligible overheads in classical observing modes. It will be equipped with a unique integral field unit that will observe in the complete spectral range with an on-sky coverage of 9.7"x6.8", composed of 17 slitlets, 0.4" wide each. Finally, a state-of-the-art polarimetric unit will allow us to obtain simultaneous full Stokes spectropolarimetry of the range between 3700 and 22000 Å.
Design and modeling of a moderate-resolution astronomic spectrograph with volume-phase holographic gratings
Author(s):
Eduard R. Muslimov;
Gennady G. Valyavin;
Sergey N. Fabrika;
Nadezhda K. Pavlycheva
Show Abstract
We present an optical design of astronomic spectrograph based on a cascade of volume-phase holographic gratings. The cascade consists of three gratings. Each of them provides moderately high spectral resolution in a narrow range of 83nm. Thus the spectrum image represents three lines covering region 430-680nm. Two versions of the scheme are described: a full-scale one with estimated resolving power of 5300-7900 and a small-sized one intended for creation of a lab prototype, which provides the resolving power of 1500-3000. Diffraction efficiency modeling confirms that the system throughput can reach 75%, while stray light caused by the gratings crosstalk is negligible. We also propose a design of image slicer and focal reducer allowing to couple the instrument with a 6m-telescope. Finally, we present concept of the instrument’s optomechanical design.
Science with OCTOCAM: a new workhorse instrument proposed for Gemini
Author(s):
Christina C. Thöne;
Antonio de Ugarte Postigo;
Alexander van der Horst;
Pete Roming
Show Abstract
OCTOCAM is an 8-channel VIS-IR (g to K-band) simultaneous imager and medium-resolution spectrograph proposed as new workhorse instrument for the 8m Gemini telescopes. It also offers additional observing modes of high time resolution, integral-field spectroscopy and spectropolarimetry, making it a very versatile instrument for many science cases in the 2020ies. A special focus of OCTOCAM will be the detection and follow-up of transient sources such as gamma-ray bursts, supernovae, magnetars, active galactic nuclei and yet to be discovered new objects, delivered by large-scale surveys like LSST available in the 2020ies. The diverse nature of transients will require the full range of OCTOCAM capabilities allowing more information in very short time about the source than with any other current instrument and adaptable almost in real time. Another main science topic will be to probe the high redshift Universe and the first stars for which OCTOCAM will be highly suited due to its wide wavelength coverage and high sensitivity. However, OCTOCAM is also suited for a large range of other science cases including transneptunian objects, exoplanets, stellar evolution and supermassive black holes. Our science team comprises more than 50 researchers reflecting the large interest of the Gemini community in the capabilities of OCTOCAM. We will highlight a few important science cases demonstrating the different capabilities of OCTOCAM and their need for the scientific community.
The Wendelstein three channel imager (3KK): alignment, commissioning, and first results
Author(s):
F. Lang-Bardl;
R. Bender;
C. Goessl;
F. Grupp;
H.-J. Hess;
J. Kaminski;
K. Hodapp;
U. Hopp;
S. Jacobson;
H. Kravcar;
A. Monna;
W. Mitsch;
J. Schlichter;
M. Wegner
Show Abstract
The Ludwig-Maximilians-Universität München operates an astrophysical observatory on the summit of Mt. Wendelstein which was equipped with a modern 2m-class robotic telescope in 20111-3. One of the two Nasmyth ports is designed to deliver the excellent (< 0.8” median) seeing of the site for a FoV of 60 arcmin2 without any corrector optics at optical and near infrared (NIR) wavebands. This port hosts a three channel imager whose design was already presented in Lang-Bardl et al. 2010.4 It is designed to efficiently support observations of targets of opportunities like Gamma-Ray-bursts or efficient photometric
redshift determination of sources identified by surveys like PanSTARS, Planck (SZ) or eROSITA. The covered wavelength range is 340 nm to 2.3 microns. The camera provides standard broadband filters (Sloan, Y, J, H, Ks) and 5 narrowband filters (OI, Hα, SII, H2, Brλ). The narrowband filters will enable deep studies of star forming regions. We present the final design of the camera, the assembly and alignment procedure performed in the laboratory before we transported the instrument to the observatory. We also show first results of the achieved on sky performance concerning image quality and efficiency of the camera in the different filter passbands.
Gamma/hadron separation in HAWC using neural networks
Author(s):
T. Capistrán ;
I. Torres;
E. Moreno
Show Abstract
The High Altitude Water Cherenkov (HAWC) Observatory is a ground based air-shower array of 300 water Cherenkov detectors (WCDs) located on the hillslide of volcano Sierra Negra, Mexico. Each WCD has 4 photomultiplier tubes (PMTs) that detect secondary particles of air-showers produced by gamma-rays and cosmic rays (CRs). Those CRs are the main problem in the gamma-ray sources analysis, therefore, we need to separate between both particles. Currently, the HAWC data is divided in 10 bins that depend on the number of PMTs activated in each event. For the suppression of CRs background, HAWC uses two variables, Compactness and PINCness, that are used to apply a simple cutoff in each bin. In this work a neural network (NN) was trained that uses these two variables as input parameters in order to obtain one output parameter and use it as a cutoff. We used simulated proton and gamma events to train the NN and we found an optimal cutoff, that we applied to the Crab Nebula. This work predicts a better gamma/hadron separation in some bins when we use Monte Carlo (MC) data.
The prototype cameras for trans-Neptunian automatic occultation survey
Author(s):
Shiang-Yu Wang;
Hung-Hsu Ling;
Yen-Sang Hu;
John C. Geary;
Yin-Chang Chang;
Hsin-Yo Chen;
Stephen M. Amato;
Pin-Jie Huang;
Jerome Pratlong;
Andrew Szentgyorgyi;
Matthew Lehner;
Timothy Norton;
Paul Jorden
Show Abstract
The Transneptunian Automated Occultation Survey (TAOS II) is a three robotic telescope project to detect the stellar occultation events generated by TransNeptunian Objects (TNOs). TAOS II project aims to monitor about 10000 stars simultaneously at 20Hz to enable statistically significant event rate. The TAOS II camera is designed to cover the 1.7 degrees diameter field of view of the 1.3m telescope with 10 mosaic 4.5k×2k CMOS sensors. The new CMOS sensor (CIS 113) has a back illumination thinned structure and high sensitivity to provide similar performance to that of the back-illumination thinned CCDs. Due to the requirements of high performance and high speed, the development of the new CMOS sensor is still in progress. Before the science arrays are delivered, a prototype camera is developed to help on the commissioning of the robotic telescope system. The prototype camera uses the small format e2v CIS 107 device but with the same dewar and also the similar control electronics as the TAOS II science camera. The sensors, mounted on a single Invar plate, are cooled to the operation temperature of about 200K as the science array by a cryogenic cooler. The Invar plate is connected to the dewar body through a supporting ring with three G10 bipods. The control electronics consists of analog part and a Xilinx FPGA based digital circuit. One FPGA is needed to control and process the signal from a CMOS sensor for 20Hz region of interests (ROI) readout.
The Gamma-ray Cherenkov Telescope, an end-to end Schwarzschild-Couder telescope prototype proposed for the Cherenkov Telescope Array
Author(s):
J. L. Dournaux;
A. Abchiche;
D. Allan;
J. P. Amans;
T. P. Armstrong;
A. Balzer;
D. Berge;
C. Boisson;
J.-J. Bousquet;
A. M. Brown;
M. Bryan;
G. Buchholtz;
P. M. Chadwick;
H. Costantini;
G. Cotter;
L. Dangeon;
M. K. Daniel;
A. De Franco;
F. De Frondat;
D. Dumas;
J. P. Ernenwein;
G. Fasola;
S. Funk;
J. Gironnet;
J. A. Graham;
T. Greenshaw;
B. Hameau;
O. Hervet;
N. Hidaka;
J.A. Hinton;
J.M. Huet;
I. Jégouzo;
T. Jogler;
T. Kawashima;
M. Kraush;
J. S. Lapington;
P. Laporte;
J. Lefaucheur;
S. Markoff;
T. Melse;
L. Mohrmann;
P. Molyneux;
S. J. Nolan;
A. Okumura;
J. P. Osborne;
R. D. Parsons;
S. Rosen;
D. Ross;
G. Rowell;
C. B. Rulten;
Y. Sato;
F. Sayède;
J. Schmoll;
H. Schoorlemmer;
M. Servillat;
H. Sol;
V. Stamatescu;
M. Stephan;
R. Stuik;
J. Sykes;
H. Tajima;
J. Thornhill;
L. Tibaldo;
C. Trichard;
J. Vink;
J. J. Watson;
R. White;
N. Yamane;
A. Zech;
A. Zink
Show Abstract
The GCT (Gamma-ray Cherenkov Telescope) is a dual-mirror prototype of Small-Sized-Telescopes proposed for the Cherenkov Telescope Array (CTA) and made by an Australian-Dutch-French-German-Indian-Japanese-UK-US consortium. The integration of this end-to-end telescope was achieved in 2015. On-site tests and measurements of the first Cherenkov images on the night sky began on November 2015. This contribution describes the telescope and plans for the pre-production and a large scale production within CTA.
The GMOX science case: resolving galaxies through cosmic time
Author(s):
Mario Gennaro;
Massimo Robberto;
Timothy Heckman;
Stephen A. Smee;
Robert Barkhouser;
Zoran Ninkov;
Angela Adamo;
George Becker;
Andrea Bellini;
Luciana Bianchi;
Arjan Bik;
Rongmon Bordoloi;
Annalisa Calamida;
Daniela Calzetti;
Gisella De Rosa;
Susana Deustua;
Jason Kalirai;
Jennifer Lotz;
John MacKenty;
Carlo Felice Manara;
Margaret Meixner;
Camilla Pacifici;
Elena Sabbi;
Kailash Sahu;
Jason Tumlinson
Show Abstract
We present the key scientific questions that can be addressed by GMOX, a Multi-Object Spectrograph selected for feasibility study as a 4th generation instrument for the Gemini telescopes. Using commercial digital micro-mirror devices (DMDs) as slit selection mechanisms, GMOX can observe hundreds of sources at R~5000 between the U and K band simultaneously. Exploiting the narrow PSF delivered by the Gemini South GeMS MCAO module, GMOX can synthesize slits as small as 40mas reaching extremely faint magnitude limits, and thus enabling a plethora of applications and innovative science. Our main scientific driver in developing GMOX has been Resolving galaxies through cosmic time: GMOX 40mas slit (at GeMS) corresponds to 300 pc at z ~ 1:5, where the angular diameter distance reaches its maximum, and therefore to even smaller linear scales at any other redshift. This means that GMOX can take spectra of regions smaller than 300 pc in the whole observable Universe, allowing to probe the growth and evolution of galaxies with unprecedented detail. GMOXs multi-object capability and high angular resolution enable efficient studies of crowded fields, such as globular clusters, the Milky Way bulge, the Magellanic Clouds, Local Group galaxies and galaxy clusters. The wide-band simultaneous coverage and the very fast slit configuration mechanisms also make GMOX ideal for follow-up of LSST transients.
PRAXIS: a near infrared spectrograph optimised for OH suppression
Author(s):
S. C. Ellis;
S. Bauer;
J. Bland-Hawthorn;
S. Case;
R. Content;
T. Fechner;
D. Giannone;
R. Haynes;
E. Hernandez;
A. J. Horton;
U. Klauser;
J. S. Lawrence;
S. G. Leon-Saval;
E. Lindley;
H.-G. Löhmannsröben;
S.-S. Min;
N. Pai;
M. Roth;
K. Shortridge;
Nicholas F. Staszak;
Julia Tims;
Pascal Xavier;
Ross Zhelem
Show Abstract
Atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. PRAXIS is a unique spectrograph, currently in the build-phase, which is fed by a fibre array that removes the OH background. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. PRAXIS will use the same fibre Bragg gratings as GNOSIS in the first implementation, and new, less expensive and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of ~1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of ~ 9 with the GNOSIS gratings and a factor of ~ 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS due to high thermal emission, low spectrograph transmission, and detector noise. PRAXIS will have extremely low thermal emission, through the cooling of all significantly emitting parts, including the fore-optics, the fibre Bragg gratings, a long length of fibre, and a fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS will achieve low detector noise through the use of a Hawaii-2RG detector, and a high throughput through an efficient VPH based spectrograph. The scientific aims of the instrument are to determine the absolute level of the interline continuum and to enable observations of individual objects via an IFU. PRAXIS will first be installed on the AAT, then later on an 8m class telescope.
Update on BOMBOLO: a 3-arm, wide-field, near-UV/optical imager for the 4-meter SOAR telescope
Author(s):
Eduardo Garcés;
Dani Guzmán;
Damien Jones;
Rodolfo Angeloni;
Thomas Puzia
Show Abstract
BOMBOLO is our instrument proposal for covering a series of scientific cases, in the not-so-explored time window of tens of seconds to minutes exposures, to be installed at the SOAR observatory. BOMBOLO is a wide field imager, capable of simultaneous, synchronous and independent observations in three different bands of the near-UV and visible wavelengths. BOMBOLO will be located at one of the Bent Cassegrain focal stations. Given its length, weight and mounting limitations, we discuss the current mechanical and opto-mechanical design of the instrument, given flexures caused by a changing gravity vector. In order to validate our designs, a Monte-Carlo simulation is used to explore different observing conditions, as the starting point for static and dynamic studies of the structure using Finite Element Analysis tools. A quick update on the current state of the instrument related to the optical design and manufacturing as well as the CCD cameras is included.
LRS2: design, assembly, testing, and commissioning of the second-generation low-resolution spectrograph for the Hobby-Eberly Telescope
Author(s):
Taylor S. Chonis;
Gary J. Hill;
Hanshin Lee;
Sarah E. Tuttle;
Brian L. Vattiat;
Niv Drory;
Briana L. Indahl;
Trent W. Peterson;
Jason Ramsey
Show Abstract
The second generation Low Resolution Spectrograph (LRS2) is a new facility instrument for the Hobby-Eberly Telescope (HET) at McDonald Observatory. Designed as a powerful spectroscopic follow-up platform, LRS2 is based on the design of the HETs new Visible Integral-field Replicable Unit Spectrograph (VIRUS) and provides integral field spectroscopy for two seeing-limited fields of 6”×12” with unity fill factor. The replicable design of VIRUS has been leveraged for LRS2 to gain broad wavelength coverage from 370 nm to 1.0 μm, spread between two fiber-fed dual-channel spectrographs that operate in unison but observe independent fields that are separated by 100”. The blue spectrograph pair, LRS2-B, covers 364≤λ (nm) ≤ 467 and 454 ≤ λ (nm)≤700 at fixed resolving powers of R =λ/δλ≈2500 and 1400, respectively, while the red spectrograph pair, LRS2-R, covers 643≤λ (nm)≤845 and 823≤λ (nm)≤1056 with both of its channels having R≈2500. In this paper, a detailed description of the instrument's design, assembly, and laboratory testing is provided in which the focus is placed on the departures from the basic framework of the design and processes previously established for VIRUS. Both LRS2 spectrograph pairs have been successfully deployed on the HET, and commissioning efforts are ongoing. Using on-sky data, the performance of the spectrograph is compared to models of the instrumental sensitivity. The measured performance of LRS2 indicates that the instrument will provide efficient spectroscopic follow-up observations of individual targets, and will be especially powerful when combined with the extensive survey capabilities of VIRUS for HETDEX.
Cryogenic near infrared spectropolarimeter for the Daniel K. Inouye Solar Telescope
Author(s):
Andre Fehlmann;
Cynthia Giebink;
Jeffrey R. Kuhn;
Ernesto J. Messersmith;
Donald L. Mickey;
Isabelle F. Scholl;
Don James;
Kirby Hnat;
Greg Schickling;
Richard Schickling
Show Abstract
The Cryogenic Near Infrared Spectropolarimeter for the Daniel K Inouye Solar Telescope is designed to measure polarized light from 0.5 to 5 μm. It uses an almost all reflective design for high throughput and an R2 echelle grating to achieve the required resolution of up to R = 100,000. The optics cooled to cryogenic temperatures reduce the thermal background allowing for IR observations of the faint solar corona. Both the spectrograph and its context imager use H2RG detector arrays with a newly designed controller to allow synchronized exposures at frame rates up to 10 Hz. All hardware has been built and tested and the key components met their design goals. 1) The cryogenic system uses mechanical closed cycle coolers which introduce vibrations. Our design uses a two stage approach with a floating mounting disk and flexible cold links to reduce these. The vibration amplitudes on all critical stages were measured and are smaller than 1μm. 2) The grating stage of the spectrograph uses a double stack of harmonic drives and an optical encoder to provide sub-arcsecond resolution and a measured repeatability of better than 0.5 arcsec.
Balloon UV experiments for astronomical and atmospheric observations
Author(s):
Sreejith A. G.;
Joice Mathew;
Mayuresh Sarpotdar;
Nirmal K.;
Ambily S.;
Ajin Prakash;
Margarita Safonova;
Jayant Murthy
Show Abstract
The ultraviolet (UV) window has been largely unexplored through balloons for astronomy. We discuss here the development of a compact near-UV spectrograph with fiber optics input for balloon flights. It is a modified Czerny-Turner system built using off-the-shelf components. The system is portable and scalable to different telescopes. The use of reflecting optics reduces the transmission loss in the UV. It employs an image-intensified CMOS sensor, operating in photon counting mode, as the detector of choice. A lightweight pointing system developed for stable pointing to observe astronomical sources is also discussed, together with the methods to improve its accuracy, e.g. using the in-house build star sensor and others. Our primary scientific objectives include the observation of bright Solar System objects such as visible to eye comets, Moon and planets. Studies of planets can give us valuable information about the planetary aurorae, helping to model and compare atmospheres of other planets and the Earth. The other major objective is to look at the diffuse UV atmospheric emission features (airglow lines), and at column densities of trace gases. This UV window includes several lines important to atmospheric chemistry, e.g. SO2, O3, HCHO, BrO. The spectrograph enables simultaneous measurement of various trace gases, as well as provides better accuracy at higher altitudes compared to electromechanical trace gas measurement sondes. These lines contaminate most astronomical observations but are poorly characterized. Other objectives may include sprites in the atmosphere and meteor ashes from high altitude burn-outs. Our recent experiments and observations with high-altitude balloons are discussed.
Development of high reflectivity coatings for large format Fabry-Perot etalons
Author(s):
M. Sigwarth;
J. Baumgartner;
A. Bell;
G. Cagnoli;
A. Fischer;
C. Halbgewachs;
F. Heidecke;
Th. J. Kentischer;
B. Kestner;
P. Kuschnir;
O. von der Lühe;
L. Pinard;
Ch. Michel;
W. J. Reichman;
B. Sassolas;
Th. Scheiffelen;
W. Schmidt
Show Abstract
The Visible Tunable Filter (VTF) is a diffraction-limited narrowband tunable instrument for imaging spectropolarimetry in the wavelength range between 520 and 860 nm. It is based on large-format Fabry Perot. The instrument will be one of the first-light instruments of the 4m aperture Daniel K. Inoue Solar Telescope (DKIST). To provide a field of view of 1 arcmin and a spectral resolution λ/Δλ of about 100.000, the required free aperture of the Fabry Perot is 250mm. The high reflectivity coatings for the Etalon plates need to meet the specifications for the reflectivity over the entire wavelength range and preserve the plate figure specifications of better λ/300, and a micro roughness of < 0.4 nm rms. Coated surfaces with similar specifications have successfully been made for reflecting mirrors on thick substrates but not for larger format Fabry-Perot systems. Ion Beam Sputtering (IBS) based coatings provide stable, homogeneous, and smooth coatings. But IBS coatings also introduce stresses to the substrate that influence the plate figure in our case at the nm level. In a joint effort with an industry partner and a French CNRS research laboratory, we developed and tested processes on small and full size substrates, to provide coated Etalon plates to the required specifications. Zygo Extreme Precision Optics, Richmond, CA, USA, is polishing and figuring the substrates, doing the metrology and FE analysis. LMA (Laboratoire Matériaux Avancés, Lyon, France) is designing and making the IBS coatings and investigating the detailed behavior of the coatings and related processes. Both partners provide experience from manufacturing coated plane optics for gravitational wave detection experiments and EUV optics. The Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany is designing and building the VTF instrument and is leading the coating development. We present the characteristics of the coatings and the substrate processing concept, as well as results from tests on sample size and from full size substrate processing. We demonstrate that the tight specifications for a single Etalon can be reached.
The PAU camera carbon fiber cryostat and filter interchange system
Author(s):
Luis Lopez;
Cristóbal Padilla;
Laia Cardiel-Sas;
Otger Ballester;
Ferràn Grañena;
Ester Majà;
Francisco J. Castander
Show Abstract
This paper describes the engineering and mechanical considerations in the design and construction of a carbon fiber containment vessel for a photometric camera. The camera is intended for installation on the 4 m William Herschel Telescope, located in Palma, Spain. The scientific objective of the camera system is to measure red-shifts of a large sample of galaxies using the photometric technique. The paper is broken down into sections, divided by the principal engineering challenges of the project; the carbon fiber vacuum vessel, the cooling systems and the precision movement systems.
Qualification of HEIDENHAIN linear encoders for picometer resolution metrology in VTF Etalons
Author(s):
Clemens Halbgewachs;
Thomas J. Kentischer;
Karsten Sändig;
Joerg Baumgartner;
Alexander Bell;
Andreas Fischer;
Stefan Funk;
Frank Heidecke;
Thomas Scheiffelen;
Wolfgang Schmidt;
Erwin Spanner;
Peter Speckbacher;
Oskar F. von der Lühe
Show Abstract
The Visible Tunable Filter (VTF) is a narrowband tunable instrument for imaging spectropolarimetry in the wavelength range between 520 and 870 nm. It is based on large-format Fabry Perots with a free aperture of 250 mm. The instrument will be one of the first-light instruments of the 4 m aperture Daniel K. Inoue Solar Telescope (DKIST) that is currently under construction on Maui (Hawaii). To provide stable and repeatable spectral scanning by tuning the air gap distance of the Etalons, a metrology system with 20 pm resolution and drift stability of better 100 pm per hour is needed. The integration of the metrology system must preserve the tight optical specifications of the Etalon plates. The HEIDENHAIN LIP 382 linear encoder system has a selected linear scale for low noise high signal interpolation. The signal period is 128nm and the interpolated signal from the sensor can be read out at 128 nm/ 14 bit = 7.8125 pm. To qualify the LIP 382 system for the VTF, we investigated the resolution and stability under nominal VTF operation conditions and verified a mounting concept for the sensor heads. We present results that demonstrate that the LIP 382 system fulfills the requirements for the VTF Etalons. We also present a design for the sensor head mounts.
MOPTOP: a multi-colour optimised optical polarimeter
Author(s):
Helen Jermak;
Iain A. Steele;
Robert J. Smith
Show Abstract
We present the design and science case for the Liverpool Telescope's fourth-generation polarimeter; MOPTOP: a Multicolour OPTimised Optical Polarimeter which is optimised for sensitivity and bi-colour observations. We introduce an optimised polarimeter which is as far as possible limited only by the photon counting efficiency of the detectors. Using a combination of CMOS cameras, a continuously rotating half-wave plate and a wire grid polarising beamsplitter, we predict we can accurately measure the polarisation of sources to ~ 1% at ~19th magnitude in 10 minutes on a 2 metre telescope. For brighter sources we anticipate much low systematics (⪅ 0.1%) than our current polarimeter. The design also gives the ability to measure polarization and photometric variability on timescales as short as a few seconds. Overall the instrument will allow accurate measurements of the intra-nightly variability of the polarisation of sources such as gamma-ray bursts and blazars (AGN orientated with the jet pointing toward the observer), allowing the constraint of magnetic field models revealing more information about the formation, ejection and collimation of jets.
The PAUCam readout electronics system
Author(s):
Jorge Jiménez ;
José M. Illa;
Laia Cardiel-Sas;
Juan de Vicente;
Javier Castilla;
Ricard Casas
Show Abstract
The PAUCam is an optical camera with a wide field of view of 1 deg x 1 deg and up to 46 narrow and broad band filters. The camera is already installed on the William Herschel Telescope (WHT) in the Canary Islands, Spain and successfully commissioned during the first period of 2015. The paper presents the main results from the readout electronics commissioning tests and include an overview of the whole readout electronics system, its configuration and current performance.
Characterization and performance of PAUCam filters
Author(s):
R. Casas;
L. Cardiel-Sas;
F. J. Castander;
C. Díaz;
J. Gaweda;
J. Jiménez Rojas;
S. Jiménez;
M. Lamensans;
C. Padilla;
F. J. Rodriguez;
E. Sanchez ;
I. Sevilla Noarbe
Show Abstract
PAUCam is a large field of view camera designed to exploit the field delivered by the prime focus corrector of the William Herschel Telescope, at the Observatorio del Roque de los Muchachos. One of the new features of this camera is its filter system, placed within a few millimeters of the focal plane using eleven trays containing 40 narrow band and 6 broad band filters, working in vacuum at an operational temperature of 250K and in a focalized beam. In this contribution, we describe the performance of these filters both in the characterization tests at the laboratory.
PLC-controlled cryostats for the BlackGEM and MeerLICHT detectors
Author(s):
Gert Raskin;
Johan Morren;
Wim Pessemier;
Steven Bloemen;
Marc Klein-Wolt;
Ronald Roelfsema;
Paul Groot;
Conny Aerts
Show Abstract
BlackGEM is an array of telescopes, currently under development at the Radboud University Nijmegen and at NOVA (Netherlands Research School for Astronomy). It targets the detection of the optical counterparts of gravitational waves. The first three BlackGEM telescopes are planned to be installed in 2018 at the La Silla observatory (Chile). A single prototype telescope, named MeerLICHT, will already be commissioned early 2017 in Sutherland (South Africa) to provide an optical complement for the MeerKAT radio array. The BlackGEM array consists of, initially, a set of three robotic 65-cm wide-field telescopes. Each telescope is equipped with a single STA1600 CCD detector with 10.5k x 10.5k 9-micron pixels that covers a 2.7 square degrees field of view. The cryostats for housing these detectors are developed and built at the KU Leuven University (Belgium). The operational model of BlackGEM requires long periods of reliable hands-off operation. Therefore, we designed the cryostats for long vacuum hold time and we make use of a closed-cycle cooling system, based on Polycold PCC Joule-Thomson coolers. A single programmable logic controller (PLC) controls the cryogenic systems of several BlackGEM telescopes simultaneously, resulting in a highly reliable, cost-efficient and maintenance-friendly system. PLC-based cryostat control offers some distinct advantages, especially for a robotic facility. Apart of temperature monitoring and control, the PLC also monitors the vacuum quality, the power supply and the status of the PCC coolers (compressor power consumption and temperature, pressure in the gas lines, etc.). Furthermore, it provides an alarming system and safe and reproducible procedures for automatic cool down and warm up. The communication between PLC and higher-level software takes place via the OPC-UA protocol, offering a simple to implement, yet very powerful interface. Finally, a touch-panel display on the PLC provides the operator with a user-friendly and robust technical interface. In this contribution, we present the design of the BlackGEM cryostats and of the PLC-based control system.
End-to-end simulations of the visible tunable filter for the Daniel K. Inouye Solar Telescope
Author(s):
Wolfgang Schmidt;
Matthias Schubert;
Monika Ellwarth;
Jörg Baumgartner;
Alexander Bell;
Andreas Fischer;
Clemens Halbgewachs;
Frank Heidecke;
Thomas Kentischer;
Oskar von der Lühe;
Thomas Scheiffelen;
Michael Sigwarth
Show Abstract
The Visible Tunable Filter (VTF) is a narrowband tunable filter system for imaging spectroscopy and spectropolarimetry based. The instrument will be one of the first-light instruments of the Daniel K. Inouye Solar Telescope that is currently under construction on Maui (Hawaii). The VTF is being developed by the Kiepenheuer Institut fuer Sonnenphysik in Freiburg as a German contribution to the DKIST. We perform end-to-end simulations of spectropolarimetric observations with the VTF to verify the science requirements of the instrument. The instrument is simulated with two Etalons, and with a single Etalon. The clear aperture of the Etalons is 250 mm, corresponding to a field of view with a diameter of 60 arcsec in the sky (42,000 km on the Sun). To model the large-scale figure errors we employ low-order Zernike polynomials (power and spherical aberration) with amplitudes of 2.5 nm RMS. We use an ideal polarization modulator with equal modulation coefficients of 3-1/2 for the polarization modulation We synthesize Stokes profiles of two iron lines (630.15 nm and 630.25 nm) and for the 854.2 nm line of calcium, for a range of magnetic field values and for several inclination angles. We estimated the photon noise on the basis of the DKIST and VTF transmission values, the atmospheric transmission and the spectral flux from the Sun. For the Fe 630.25 nm line, we obtain a sensitivity of 20 G for the longitudinal component and for 150 G for the transverse component, in agreement with the science requirements for the VTF.
Bokeh mirror alignment for Cherenkov telescopes
Author(s):
S. A. Mueller;
J. Adam;
M. L. Ahnen;
D. Baack;
M. Balbo;
M. Bergmann;
A. Biland;
M. Blank;
T. Bretz;
K. A. Bruegge;
J. Buss;
A. Dmytriiev;
D. Dorner;
S. Einecke;
C. Hempfling;
D. Hildebrand;
G. Hughes;
L. Linhoff;
K. Mannheim;
D. Neise;
A. Neronov;
M. Noethe;
A. Paravac;
F. Pauss;
W. Rhode;
A. Shukla;
F. Temme;
J. Thaele;
R. Walter
Show Abstract
Segmented imaging reflectors are a great choice for Imaging Atmospheric Cherenkov Telescopes (IACTs). However, the alignment of the individual mirror facets is challenging. We align a segmented reflector by observing and optimizing its Bokeh function. Bokeh alignment can already be done with very little resources and little preparation time. Further, Bokeh alignment can be done anytime, even during the day. We present a first usage of Bokeh alignment on FACT, a 4m IACT on Canary Island La Palma, Spain and further a first Bokeh alignment test on the CTA MST IACT prototype in Brelin Adlershof.
First results and future plans for the Canarias Infrared Camera Experiment (CIRCE) for the Gran Telescopio Canarias
Author(s):
Alan Garner;
Stephen S. Eikenberry;
Miguel Charcos;
Yigit Dallilar;
Michelle Edwards;
Nestor Lasso-Cabrera;
Richard D. Stelter;
Antonio Marin-Franch;
S. Nicholas Raines;
Kendall Ackley;
John G. Bennett;
Javier A. Cenarro ;
Brian Chinn;
Veronica H. Donoso;
Raymond Frommeyer;
Kevin Hanna;
Michael D. Herlevich;
Jeff Julian;
Paola Miller;
Scott Mullin;
Charles H. Murphey;
Christopher Packham;
Frank Varosi;
Claudia Vega;
Craig Warner;
Anamparambu N. Ramaprakash;
Mahesh Burse;
Sujit Punnadi;
Pravinkumar Chordia;
Andreas Gerarts;
Héctor de Paz Martín;
María Martín Calero;
Riccardo Scarpa;
Sergio Fernandez Acosta;
William Miguel Hernández Sánchez;
Benjamin Siegel;
Francisco Francisco Pérez;
Himar D. Viera Martín;
José A. Rodríguez Losada;
Agustín Nuñez;
Álvaro Tejero;
Carlos E. Martín González;
César Cabrera Rodríguez;
Jordi Molgó Sendra;
J. Esteban Rodriguez;
J. Israel Fernádez Cáceres;
Luis A. Rodríguez García;
Manuel Huertas Lopez;
Raul Dominguez;
Tim Gaggstatter;
Antonio Cabrera-Lavers;
Stefan Geier;
Peter Pessev;
Ata Sarajedini;
A. J. Castro-Tirado
Show Abstract
CIRCE is a near-infrared (1-2.5 micron) imager (including low-resolution spectroscopy and polarimetery) in operation as a visitor instrument on the Gran Telescopio Canarias 10.-4m tele scope. It was built largely by graduate students and postdocs, with help from the UF Astronomy engineering group, and is funded by the University of Florida and the U.S. National Science Foundation. CIRCE is helping to fill the gap in time between GTC first light and the arrival of EMIR, and will also provide the following scientific capabilities to compliment EMIR after its arrival: high-resolution imaging, narrowband imaging, high-time-resolution photometry, polarimetry, and low-resolution spectroscopy. There are already scientific results from CIRCE, some of which we will review. Additionally, we will go over the observing modes of CIRCE, including the two additional modes that were added during a service and upgrading run in March 2016.
TAUKAM: a new prime-focus camera for the Tautenburg Schmidt Telescope
Author(s):
Bringfried Stecklum;
Jochen Eislöffel;
Sylvio Klose;
Uwe Laux;
Tom Löwinger;
Helmut Meusinger;
Michael Pluto;
Johannes Winkler;
Frank Dionies
Show Abstract
TAUKAM stands for "TAUtenburg KAMera", which will become the new prime-focus imager for the Tautenburg Schmidt telescope. It employs an e2v 6kx6k CCD and is under manufacture by Spectral Instruments Inc. We describe the design of the instrument and the auxiliary components, its specifications as well as the concept for integrating the device into the telescope infrastructure. First light is foreseen in 2017. TAUKAM will boost the observational capabilities of the telescope for what concerns optical wide-field surveys.
Calibrating the SNfactory Integral Field Spectrograph (SNIFS) with SCALA
Author(s):
Daniel Küsters;
Simona Lombardo;
Marek Kowalski;
Greg Aldering;
Jakob Nordin;
Mickael Rigault
Show Abstract
The SNIFS CALibration Apparatus (SCALA), a device to calibrate the Supernova Integral Field Spectrograph on the University Hawaii 2.2m telescope, was developed and installed in Spring 2014. SCALA produces an artificial planet with a diameter of 1° and a constant surface brightness. The wavelength of the beam can be tuned between 3200 Å and 10000 Å and has a bandwidth of 35 Å. The amount of light injected into the telescope is monitored with NIST calibrated photodiodes. SCALA was upgraded in 2015 with a mask installed at the entrance pupil of the UH88 telescope, ensuring that the illumination of the telescope by stars is similar to that of SCALA. With this setup, a first calibration run was performed in conjunction with the spectrophotometric observations of standard stars. We present first estimates for the expected systematic uncertainties of the in-situ calibration and discuss the results of tests that examine the influence of stray light produced in the optics.
Design and development of control unit and software for the ADFOSC instrument of the 3.6 m Devasthal optical telescope
Author(s):
T. S. Kumar
Show Abstract
In this paper, we describe the details of control unit and GUI software for positioning two filter wheels, a slit wheel and a grism wheel in the ADFOSC instrument. This is a first generation instrument being built for the 3.6 m Devasthal optical telescope. The control hardware consists of five electronic boards based on low cost 8-bit PIC microcontrollers and are distributed over I2C bus. The four wheels are controlled by four identical boards which are configured in I2C slave mode while the fifth board acts as an I2C master for sending commands to and receiving status from the slave boards. The master also communicates with the interfacing PC over TCP/IP protocol using simple ASCII commands. For moving the wheels stepper motors along with suitable amplifiers have been employed. Homing after powering ON is achieved using hall effect sensors. By implementing distributed control units having identical design modularity is achieved enabling easier maintenance and upgradation. A GUI based software for commanding the instrument is developed in Microsoft Visual C++. For operating the system during observations the user selects normal mode while the engineering mode is available for offering additional flexibility and low level control during maintenance and testing. A detailed time-stamped log of commands, status and errors are continuously generated. Both the control unit and the software have been successfully tested and integrated with the ADFOSC instrument.
The opto-mechanical design for GMOX: a next-generation instrument concept for Gemini
Author(s):
Stephen A. Smee;
Robert Barkhouser;
Massimo Robberto;
Zoran Ninkov;
Mario Gennaro;
Timothy M. Heckman
Show Abstract
We present the opto-mechanical design of GMOX, the Gemini Multi-Object eXtra-wide-band spectrograph, a potential next-generation (Gen-4 #3) facility-class instrument for Gemini. GMOX is a wide-band, multi-object, spectrograph with spectral coverage spanning 350 nm to 2.4 um with a nominal resolving power of R 5000. Through the use of Digital Micromirror Device (DMD) technology, GMOX will be able to acquire spectra from hundreds of sources simultaneously, offering unparalleled flexibility in target selection. Utilizing this technology, GMOX can rapidly adapt individual slits to either seeing-limited or diffraction-limited conditions. The optical design splits the bandpass into three arms, blue, red, and near infrared, with the near-infrared arm being split into three channels covering the Y+J band, H band, and K band. A slit viewing camera in each arm provides imaging capability for target acquisition and fast-feedback for adaptive optics control with either ALTAIR (Gemini North) or GeMS (Gemini South). Mounted at the Cassegrain focus, GMOX is a large (1.3 m x 2.8 m x 2.0 m) complex instrument, with six dichroics, three DMDs (one per arm), five science cameras, and three acquisition cameras. Roughly half of these optics, including one DMD, operate at cryogenic temperature. To maximize stiffness and simplify assembly and alignment, the opto-mechanics are divided into three main sub-assemblies, including a near-infrared cryostat, each having sub-benches to facilitate ease of alignment and testing of the optics. In this paper we present the conceptual opto-mechanical design of GMOX, with an emphasis on the mounting strategy for the optics and the thermal design details related to the near-infrared cryostat.
The optical design of GMOX: a next-generation instrument concept for Gemini
Author(s):
Robert Barkhouser;
Massimo Robberto;
Stephen A. Smee;
Zoran Ninkov;
Mario Gennaro;
Timothy Heckman
Show Abstract
We present the optical design of GMOX, the Gemini Multi-Object eXtra-wide-band spectrograph. GMOX was selected as part of the Gemini Instrument Feasibility Study to develop capabilities and requirements for the next facility instrument (Gen4#3) for the observatory. We envision GMOX covering the entire optical/near-IR wavelength range accessible from the ground, from 3500 Å in the U band up to 2.4 μm in the K band, with nominal resolving power R≃5,000. To maximize efficiency, the bandpass is split into three spectrograph arms - blue, red, and near-infrared - with the near-infrared arm further split into three channels covering the Y+J, H, and K bands. At the heart of each arm is a Digital Micromirror Device (DMD) serving as a programmable slit array. This technology will enable GMOX to simultaneously acquire hundreds of spectra of faint sources in crowded fields with unparalleled spatial resolution, optimally adapting to both seeing-limited and diffraction limited conditions provided by ALTAIR and GeMS at Gemini North and South, respectively. Fed by GeMS at f/33, GMOX can synthesize slits as small as 40 mas (corresponding to a single HST/WFC3 CCD pixel) over its entire 85”x45” field of view. With either ALTAIR or the native telescope focal ratio of f/16, both the slit and field sizes double. In this paper we discuss the conceptual optical design of GMOX including, for each arm: the pre-slit optics, DMD slit array, off-axis Schmidt collimator, VPH grating, and refractive spectrograph and slit-viewing cameras.
Blue camera of the Keck cosmic web imager, fabrication and testing
Author(s):
Constance Rockosi;
David Cowley;
Jerry Cabak;
David Hilyard;
Terry Pfister
Show Abstract
The Keck Cosmic Web Imager (KCWI) is a new facility instrument being developed for the W. M. Keck Observatory and funded for construction by the Telescope System Instrumentation Program (TSIP) of the National Science Foundation (NSF). KCWI is a bench-mounted spectrograph for the Keck II right Nasmyth focal station, providing integral field spectroscopy over a seeing-limited field up to 20" x 33" in extent. Selectable Volume Phase Holographic (VPH) gratings provide high efficiency and spectral resolution in the range of 1000 to 20000. The dual-beam design of KCWI passed a Preliminary Design Review in summer 2011. The detailed design of the KCWI blue channel (350 to 700 nm) is now nearly complete, with the red channel (530 to 1050 nm) planned for a phased implementation contingent upon additional funding. KCWI builds on the experience of the Caltech team in implementing the Cosmic Web Imager (CWI), in operation since 2009 at Palomar Observatory. KCWI adds considerable flexibility to the CWI design, and will take full advantage of the excellent seeing and dark sky above Mauna Kea with a selectable nod-and-shuffle observing mode. In this paper, models of the expected KCWI sensitivity and background subtraction capability are presented, along with a detailed description of the instrument design. The KCWI team is lead by Caltech (project management, design and implementation) in partnership with the University of California at Santa Cruz (camera optical and mechanical design) and the W. M. Keck Observatory (program oversight and observatory interfaces). The optical design of the blue camera for the Keck Cosmic Web Imager (KCWI) by Harland Epps of the University of California, Santa Cruz is a lens assembly consisting of eight spherical optical elements. Half the elements are calcium fluoride and all elements are air spaced. The design of the camera barrel is unique in that all the optics are secured in their respective cells with an RTV annulus without additional hardware such as retaining rings. The optical design and the robust lens mounting concept has allowed UCO/Lick to design a straightforward lens camera assembly. However, alignment sensitivity is a strict 15 μm for most elements. This drives the fabrication, assembly, and performance of the camera barrel.
SIOUX project: a simultaneous multiband camera for exoplanet atmospheres studies
Author(s):
Jean Marc Christille;
Aldo Stefano Bonomo;
Francesco Borsa;
Deborah Busonero;
Paolo Calcidese;
Riccardo Claudi;
Mario Damasso;
Paolo Giacobbe;
Emilio Molinari;
Emanuele Pace;
Alberto Riva;
Alesandro Sozzetti;
Giorgio Toso;
Daniela Tresoldi
Show Abstract
The exoplanet revolution is well underway. The last decade has seen order-of-magnitude increases in the number of known planets beyond the Solar system. Detailed characterization of exoplanetary atmospheres provide the best means for distinguishing the makeup of their outer layers, and the only hope for understanding the interplay between initial composition chemistry, temperature-pressure atmospheric profiles, dynamics and circulation. While pioneering work on the observational side has produced the first important detections of atmospheric molecules for the class of transiting exoplanets, important limitations are still present due to the lack of systematic, repeated measurements with optimized instrumentation at both visible (VIS) and near-infrared (NIR) wavelengths. It is thus of fundamental importance to explore quantitatively possible avenues for improvements. In this paper we report initial results of a feasibility study for the prototype of a versatile multi-band imaging system for very high-precision differential photometry that exploits the choice of specifically selected narrow-band filters and novel ideas for the execution of simultaneous VIS and NIR measurements. Starting from the fundamental system requirements driven by the science case at hand, we describe a set of three opto-mechanical solutions for the instrument prototype: 1) a radial distribution of the optical flux using dichroic filters for the wavelength separation and narrow-band filters or liquid crystal filters for the observations; 2) a tree distribution of the optical flux (implying 2 separate foci), with the same technique used for the beam separation and filtering; 3) an 'exotic' solution consisting of the study of a complete optical system (i.e. a brand new telescope) that exploits the chromatic errors of a reflecting surface for directing the different wavelengths at different foci. In this paper we present the first results of the study phase for the three solutions, as well as the results of two laboratory prototypes (related to the first two options), that simulate the most critical aspects of the future instrument.
Concepts of the mosaic array of numerous ultra-small lens (MANUL) design
Author(s):
A. Pál;
L. Mészáros
Show Abstract
In order to provide a continuous, multi-color time-domain surveying of the brightest regime of the naked-eye optical sky, we designed the Mosaic Array of Numerous Ultrasmall Lens (MANUL). This device is a palm-sized “astronomical observatory,” featuring optics, filters and all necessary electronics (including a TCP/IP-based downlink), all are mounted on 2-inch printed circuit boards. Based on these units, a modular and mosaic arrangement of CMOS imaging sensors with an effective resolution of 1’/pixel can be built. Here we introduce the main design concepts, the early prototyping and the results of the preliminary photometric quality analysis of this initiative.
DKIST visible broadband imager alignment in laboratory: first results
Author(s):
Predrag Sekulic;
Scott B. Gregory;
Steve L. Hegwer;
Andrew Ferayorni;
Friedrich Woeger
Show Abstract
The Visible Broadband Imager (VBI) Blue and Red channels are the first Daniel K. Inouye Solar Telescope (DKIST) instruments that have been aligned and tested in a laboratory. This paper describes the optical alignment method of the VBI as performed in the laboratory. The objective of this preliminary alignment is to test and validate the optical alignment method that will be used during final alignment on the telescope, to measure the VBI performances and to verify that it meets specification. The optical alignment method is defined by three major steps. The first step is realized by combining the optical and mechanical models into the Spatial Analyzer (SA) software, and extracting the data serving as target values during alignment. The second step is the mechanical alignment and allows to accurately position the optics in the instrument coordinate system by using a Coordinate Measurement Machine (CMM) arm and a theodolite. This step has led to a great initial positioning and has allowed reaching an initial wavefront error before optical alignment close to the specification. The last step, performed by interferometry, allows fine alignment to compensate the residual aberrations created by misalignment and manufacturing tolerances. This paper presents also an alignment method to compute the shifts and tilts of compensating lenses to correct the residual aberrations. This paper describes first results of the VBI instruments performances measured in the laboratory and confirm the validity of the alignment process that will be reproduced during final alignment on the telescope.
Nanoradian ground-based astrometry, optical navigation, and artificial reference stars
Author(s):
Chengxing Zhai;
Michael Shao;
Abhijit Biswas;
Todd Ely;
Christopher Jacobs;
Joseph Lazio;
Tomas Martin-Mur;
William Owen Jr.;
Mike Rud;
Navtej Saini;
Jagmit Sandhu;
Slava Turyshev;
Thomas Werne
Show Abstract
Spacecraft carrying optical communication lasers can be treated as artificial stars, whose relative astrometry to Gaia reference stars provides spacecraft positions in the plane-of-sky for optical navigation. To be comparable to current Deep Space Network delta-Differential One-way Ranging measurements, thus sufficient for navigation, nanoradian optical astrometry is required. Here we describe our error budget, techniques for achieving nanoradian level ground-base astrometry, and preliminary results from a 1 m telescope. We discuss also how these spacecraft may serve as artificial reference stars for adaptive optics, high precision astrometry to detect exoplanets, and tying reference frames defined by radio and optical measurements.
Throughput of commercial photographic camera lenses for use in astronomical systems
Author(s):
D. Q. Nagasawa;
N. Mondrik;
J. L. Marshall;
D. L. DePoy;
L. Schmidt;
B. Hill;
L. Turner;
J. P. Rheault
Show Abstract
We present measurements of the spectral response function of commercially-available Nikon 35mm photographic camera lenses for use in astronomical instrumentation. Our motivation for this work stems from the fact that several astronomical imaging systems have been deployed or proposed using this type of commercial lens. We have performed measurements of the relative and absolute spectral response function of five commercially-available photographic lenses. These measurements show that these lenses generally have >50% throughput across the entire optical window of 400nm < λ < 800nm.
Okayama astrophysical observatory wide-field camera: status and performance
Author(s):
Kenshi Yanagisawa;
Yasuhiro Shimizu;
Kiichi Okita;
Daisuke Kuroda;
Hironori Tsutsui;
Hiroyuki Toda;
Hideyuki Izumiura;
Michitoshi Yoshida;
Koji Ohta;
Nobuyuki Kawai
Show Abstract
Okayama Astrophysical Observatory Wide Field Camera is a near-infrared (0.9-2.5 μm) survey telescope, built as a renewal of 0.91 m classical Cassegrain telescope. The optics is composed of forward Cassegrain and quasi Schmidt, which yield an effective image circle of Φ51 mm. A HAWAII-1 PACE detector is placed at the focal plane, which gives a field of view of 0.48 deg.×0.48 deg. with image scale of 1.67 arcsec/pix. OAOWFC is used to monitor the Galactic plane for variability and search for EM counterpart of gravitational wave sources.
Efficient coupling of starlight into single mode photonics using Adaptive Injection (AI)
Author(s):
Barnaby Norris;
Nick Cvetojevic;
Simon Gross;
Alexander Arriola;
Peter Tuthill;
Jon Lawrence;
Samuel Richards;
Michael Goodwin;
Jessica Zheng
Show Abstract
Using single-mode fibres in astronomy enables revolutionary techniques including single-mode interferometry and spectroscopy. However, injection of seeing-limited starlight into single mode photonics is extremely difficult. One solution is Adaptive Injection (AI). The telescope pupil is segmented into a number of smaller subapertures each with size ~ r0, such that seeing can be approximated as a single tip / tilt / piston term for each subaperture, and then injected into a separate fibre via a facet of a segmented MEMS deformable mirror. The injection problem is then reduced to a set of individual tip tilt loops, resulting in high overall coupling efficiency.
Concept design of an 80-dual polarization element cryogenic phased array camera for the Arecibo Radio Telescope
Author(s):
German Cortes-Medellin;
Stephen Parshley;
Donald B. Campbell;
Karl F. Warnick;
Brian D. Jeffs;
Rajagopalan Ganesh
Show Abstract
This paper presents the current concept design for ALPACA (Advanced L-Band Phased Array Camera for Arecibo) an L-Band cryo-phased array instrument proposed for the 305 m radio telescope of Arecibo. It includes the cryogenically cooled front-end with 160 low noise amplifiers, a RF-over-fiber signal transport and a digital beam former with an instantaneous bandwidth of 312.5 MHz per channel. The camera will digitally form 40 simultaneous beams inside the available field of view of the Arecibo telescope optics, with an expected system temperature goal of 30 K.
Astrophysical Research Consortium Telescope Imaging Camera (ARCTIC) facility optical imager for the Apache Point Observatory 3.5m telescope
Author(s):
Joseph Huehnerhoff;
William Ketzeback;
Alaina Bradley;
Jack Dembicky;
Caitlin Doughty;
Suzanne Hawley;
Courtney Johnson;
Mark Klaene;
Ed Leon;
Russet McMillan;
Russell Owen;
Conor Sayres;
Tyler Sheen;
Alysha Shugart
Show Abstract
The Astrophysical Research Consortium Telescope Imaging Camera, ARCTIC, is a new optical imaging camera now in use at the Astrophysical Research Consortium (ARC) 3.5m telescope at Apache Point Observatory (APO). As a facility instrument, the design criteria broadly encompassed many current and future science opportunities, and the components were built for quick repair or replacement, to minimize down-time. Examples include a quick change shutter, filter drive components accessible from the exterior and redundant amplifiers on the detector. The detector is a Semiconductor Technology Associates (STA) device with several key properties (e.g. high quantum efficiency, low read-noise, quick readout, minimal fringing, operational bandpass 350-950nm). Focal reducing optics (f/10.3 to f/8.0) were built to control aberrations over a 7.8'x7.8' field, with a plate scale of 0.11" per 0.15 micron pixel. The instrument body and dewar were designed to be simple and robust with only two components to the structure forward of the dewar, which in turn has minimal feedthroughs and permeation areas and holds a vacuum <10-8 Torr. A custom shutter was also designed, using pneumatics as the driving force. This device provides exceptional performance and reduces heat near the optical path. Measured performance is repeatable at the 2ms level and offers field uniformity to the same level of precision. The ARCTIC facility imager will provide excellent science capability with robust operation and minimal maintenance for the next decade or more at APO.
Status of Focal Plane Instrumentation (FPI) project of the 4m DAG telescope
Author(s):
Onur Keskin;
Sinan K. Yerli;
Cahit Yeşilyaprak;
Tolga Guver;
Sinan Aliş;
F. Korhan Yelkenci;
B. Bülent Güçsav;
Mehtap Ö. Ozbey Arabaci;
Ayşe Erol
Show Abstract
DAG (Eastern Anatolia Observatory in Turkish) will be the newest and largest (4m) observatory of Turkey in both optical (VIS) and near-infrared (NIR) with its robust observing site infrastructure. The telescope is designed¬ to house 2 Nasmyth platforms which will be dedicated to NIR and VIS observations. A collaboration has recently been established among four Turkish universities including FMV Işık University (for adaptive optics systems), Middle East Technical University (for measurement, test and calibration purposes), Istanbul University (for new technology instruments, e.g. MKIDs) and as the coordinator Ataturk University (for obtaining NIR and VIS instruments). In this paper the status of the recently approved FPI project and its aims are presented and possible collaboration opportunities are emphasized.
Design of a derotator for the 4 m DAG telescope
Author(s):
Jérémie Baudet;
Laurent Jolissaint;
Onur Keskin;
Cahit Yesilyaprak;
Sinan K. Yerli
Show Abstract
This paper summarize our work on the design of a field derotator for the adaptive optics instruments Nasmyth platform of DAG (Dogu Anadolu Gozlemevi), a new 4 m telescope for astronomical observations near the city of Erzurum, Turkey. While the telescope follows an astronomical object, its pupil sees a rotation of the object around the optical axis which depends on the telescope geographic coordinate and the object sky coordinate. This effect is called the field rotation. This rotation needs to be compensated during the astronomical object data acquisition. In this report we demonstrate the feasibility of placing the derotator (a K-mirror design) in the telescope fork central hole and propose a preliminary design, considering flexures.
The Zwicky Transient Facility Camera
Author(s):
Richard Dekany;
Roger M. Smith;
Justin Belicki;
Alexandre Delacroix;
Gina Duggan;
Michael Feeney;
David Hale;
Stephen Kaye;
Jennifer Milburn;
Patrick Murphy;
Michael Porter;
Daniel J. Reiley;
Reed L. Riddle;
Hector Rodriguez;
Eric C. Bellm
Show Abstract
The Zwicky Transient Facility Camera (ZTFC) is a key element of the ZTF Observing System, the integrated system of optoelectromechanical instrumentation tasked to acquire the wide-field, high-cadence time-domain astronomical data at the heart of the Zwicky Transient Facility. The ZTFC consists of a compact cryostat with large vacuum window protecting a mosaic of 16 large, wafer-scale science CCDs and 4 smaller guide/focus CCDs, a sophisticated vacuum interface board which carries data as electrical signals out of the cryostat, an electromechanical window frame for securing externally inserted optical filter selections, and associated cryo-thermal/vacuum system support elements. The ZTFC provides an instantaneous 47 deg2 field of view, limited by primary mirror vignetting in its Schmidt telescope prime focus configuration. We report here on the design and performance of the ZTF CCD camera cryostat and report results from extensive Joule-Thompson cryocooler tests that may be of broad interest to the instrumentation community.
Wide field of view spectroscopy using solid Fabry-Perot interferometers
Author(s):
Jonathan Nikoleyczik;
Alexander Kutyrev;
Harvey Moseley;
Sylvain Veilleux
Show Abstract
We present a high resolution spectrometer consisting of dual solid Fabry-Perot Interferometers (FPI). Each FPI is made of a single piece of L-BBH2 glass which has a high index of refraction n~2.07. Each is then coated with partially reflective mirrors to achieve a spectral resolution of R~30,000. Running the FPIs in tandem reduces the overlapping orders and allows for a much wider free spectral range and higher contrast. Tuning of the FPIs is achieved by adjusting the temperature and thus changing the FPI gap and the refractive index of the material. The spectrometer then moves spatially in order to get spectral information at every point in the field of view. We select spectral lines for further analysis and create maps of the line depths across the field. Using this technique we are able to measure the fluorescence of chlorophyll in plants and observe zodiacal light. In the chlorophyll analysis we are able to detect chlorophyll fluorescence using the line depth in a plant using the sky as a reference solar spectrum. This instrument has possible applications in either a cubesat or aerial observations to measure bulk plant activity over large areas.
COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality
Author(s):
Alan M. Watson;
Salvador Cuevas Cardona;
Luis C. Alvarez Nuñez;
Fernando Ángeles;
Rosa L. Becerra-Godínez;
Oscar Chapa;
Alejandro S. Farah;
Jorge Fuentes-Fernández;
Liliana Figueroa;
Rosalía Langarica Lebre;
Fernando Quiróz;
Carlos G. Román-Zúñiga;
Jaime Ruíz-Diáz-Soto;
Carlos Tejada;
Silvio J. Tinoco
Show Abstract
COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited fast-guiding imager. Since the telescope is small, fast guiding will provide diffraction-limited image quality over a field of at least 1 arcmin and with coverage of a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the at the Observatorio Astronómico Nacional in Sierra San Pedro Mártir, México, during 2016 and the diffraction-limited imager will follow in 2017.
Optical design of COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality
Author(s):
Jorge Fuentes-Fernández;
Salvador Cuevas ;
Alan M. Watson;
Oscar Chapa
Show Abstract
COATLI is a new instrument and telescope that will provide 0.3 arcsec FWHM images from 550 to 920 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited imager. The imager has a steering mirror for fast guiding, a blue channel using a EMCCD from 400 to 550 nm to measure image motion, a red channel using a standard CCD from 550 to 920 nm, and an active optics system based on a deformable mirror to compensate static aberrations in the red channel. Since the telescope is small, fast guiding will provide diffraction-limited image quality in the red channel over a large fraction of the sky, even in relatively poor seeing. COATLI will be installed at the Observatorio Astronomico Nacional in Baja California, Mexico, in September 2016 and will operate initially with a simple interim imager. The definitive COATLI instrument will be installed in 2017. In this paper, we present some of the details of the optical design of the instrument.
Systems design of COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality
Author(s):
Salvador Cuevas ;
Rosalia Langarica;
Alan M. Watson;
Jorge Fuentes-Fernández;
Fernando Ángeles;
Alejandro S. Farah;
Liliana Figueroa;
Rosa L. Becerra-Godínez;
Oscar Chapa;
Carlos G. Román-Zúñiga;
Fernando Quiróz;
Carlos Tejada;
Luis C. Álvarez-Núñez;
Jaime Ruz;
Silvio J. Tinoco
Show Abstract
COATLI is a new instrument and telescope that will provide 0.3 arcsec FWHM images from 550 to 920 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited imager. The imager has a steering mirror for fast guiding, a blue channel using an EMCCD from 400 to 550 nm to measure image motion, a red channel using a standard CCD from 550 to 920 nm, and an active optics system based on a deformable mirror to compensate static aberrations in the red channel. Since the telescope is small, fast guiding will provide diffraction-limited image quality in the red channel over a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the Observatorio Astronómico Nacional in Sierra San Pedro Mártir, Baja California, México, in 2016 and will initially operate with a simple interim imager. The definitive COATLI instrument will be installed in 2017. In this work we present the general optomechanical and control electronics design of COATLI.
Conception of a near-IR spectrometer for ground-based observations of massive stars
Author(s):
C. Kintziger;
R. Desselle;
J. Loicq;
G. Rauw;
P. Rochus
Show Abstract
In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument that intends to observe massive stars. Starting from the derivation of theoretical relationships from the scientific requirements and telescope characteristics, the entire optical design of the spectrograph is presented. Specific optical elements, such as a toroidal lens, are introduced to improve the instrument’s performances. Then, the verification of predicted optical performances is investigated through optical analyses such as resolution checking. Eventually, the star positioning system onto the central fiber core is explained.
The Fly's Eye camera system: new results with an autonomously observing telescope
Author(s):
L. Mészáros;
A. Pal;
A. Jaskó;
G. Csépány;
Gy. Mező;
K. Vida;
K. Oláh
Show Abstract
The Fly's Eye camera system is a multiple-passband full-sky surveying instrument employing 19 wide-field cameras in a mosaic arrangement on a spherical frame. The cameras equipped with fast focal ratio lenses and Sloan filters. The cameras are supported by single mount while the sidereal tracking, i.e. the compensation for the apparent celestial rotation is performed by a hexapod mount. As discussed in our earlier design-related publications, this tracking is unavoidable when considering 0:3 gigapixel imaging, a field-of-view diameter of 120° and exposure times around a few minutes. With this camera system we intend to perform time-domain astronomy and observe several kind of astronomical phenomena based on variability.
An airborne infrared spectrometer for solar eclipse observations
Author(s):
Jenna Samra;
Peter Cheimets;
Edward DeLuca;
John Galeros;
Thomas Gauron;
Leon Golub;
Giora Guth;
Edward Hertz;
Philip Judge;
Serge Koutchmy;
Vanessa Marquez
Show Abstract
This paper presents the design of an innovative solar spectrometer that will y on the NSF/NCAR Gulfstream V High-Performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) during the 2017 solar eclipse. The airborne infrared spectrometer (AIR-Spec) is groundbreaking in two aspects: it will image infrared coronal emission lines that have never been measured, and it will bring high resolution imaging to GV HIAPER. The instrument development faces the challenges of achieving adequate resolution and signal-to-noise ratio in a compact package mounted to a noisy moving platform. To ensure that AIR-Spec meets its research goals, the instrument is undergoing pre-flight modeling and testing. The results are presented with reference to the instrument requirements.
Project PANOPTES: a citizen-scientist exoplanet transit survey using commercial digital cameras
Author(s):
Wilfred T. Gee;
Olivier Guyon;
Josh Walawender;
Nemanja Jovanovic;
Luc Boucher
Show Abstract
Project PANOPTES (http://www.projectpanoptes.org) is aimed at establishing a collaboration between professional astronomers, citizen scientists and schools to discover a large number of exoplanets with the transit technique. We have developed digital camera based imaging units to cover large parts of the sky and look for exoplanet transits. Each unit costs approximately $5000 USD and runs automatically every night. By using low-cost, commercial digital single-lens reflex (DSLR) cameras, we have developed a uniquely cost-efficient system for wide field astronomical imaging, offering approximately two orders of magnitude better etendue per unit of cost than professional wide-field surveys. Both science and outreach, our vision is to have thousands of these units built by schools and citizen scientists gathering data, making this project the most productive exoplanet discovery machine in the world.
Stability of the FOCES spectrograph using an astro-frequency comb as calibrator
Author(s):
Anna Brucalassi;
Frank Grupp;
Hanna Kellermann;
Liang Wang;
Florian Lang-Bardl;
Nils Baisert;
Shao Ming Hu;
Ulrich Hopp;
Ralf Bender
Show Abstract
We present the results of a series of measurements conducted using the upgraded Fiber Optic Cassegrain Echelle Spectrograph (FOCES)1 intended to be operated at the 2.0 m Fraunhofer Telescope at the Wendelstein Observatory (Germany) in combination with a laser frequency comb as calibrator. Details about the laboratory set-up of the system integrated with FOCES are shown. Different analysis techniques are applied to investigate the calibration precision and the medium-long term stability of the system in term of changes in stellar radial velocity.
Conceptual design of wide-field focal plane with InGaAs image sensors
Author(s):
Y. Komiyama;
H. Nakaya;
N. Kashikawa;
T. Uchida
Show Abstract
We present a conceptual design to implement wide-field focal plane assembly with InGaAs image sensors which are being tested intensively and reveled to be promising for astronomical use. InGaAs image sensors are sensitive up to 1.7 microns and would open a new window for the wide-field near-infrared (NIR) imaging survey once large format sensors are developed. The sensors are not necessarily cooled down to below 100 K, which is the case for prevailing NIR image sensors such as HgCdTe, enabling us to develop the NIR camera based on the technique developed for the CCD camera in optical wavelength. The major technical challenges to employ InGaAS image sensors for wide-field NIR camera are implementation of focal plane assembly and thermal design. In this article, we discuss these difficulties and show how we can conquer based on our experience to build Hyper Suprime-Cam, which is a wide-field imager with 116 2k4k CCDs attached to Subaru Telescope.
Dramatic robustness of a multiple delay dispersed interferometer to spectrograph errors: how mixing delays reduces or cancels wavelength drift
Author(s):
David J. Erskine;
E. Linder;
E. Wishnow;
J. Edelstein;
M. Sirk;
P. Muirhead;
J. Lloyd;
A. Kim
Show Abstract
We describe demonstrations of remarkable robustness to instrumental noises by using a multiple delay externally dispersed interferometer (EDI) on stellar observations at the Hale telescope. Previous observatory EDI demonstrations used a single delay. The EDI (also called “TEDI”) boosted the 2,700 resolution of the native TripleSpec NIR spectrograph (950-2450 nm) by as much as 10x to 27,000, using 7 overlapping delays up to 3 cm. We observed superb rejection of fixed pattern noises due to bad pixels, since the fringing signal responds only to changes in multiple exposures synchronous to the applied delay dithering. Remarkably, we observed a ~20x reduction of reaction in the output spectrum to PSF shifts of the native spectrograph along the dispersion direction, using our standard processing. This allowed high resolution observations under conditions of severe and irregular PSF drift otherwise not possible without the interferometer. Furthermore, we recently discovered an improved method of weighting and mixing data between pairs of delays that can theoretically further reduce the net reaction to PSF drift to zero. We demonstrate a 350x reduction in reaction to a native PSF shift using a simple simulation. This technique could similarly reduce radial velocity noise for future EDI’s that use two delays overlapped in delay space (or a single delay overlapping the native peak). Finally, we show an extremely high dynamic range EDI measurement of our ThAr lamp compared to a literature ThAr spectrum, observing weak features (~0.001x height of nearest strong line) that occur between the major lines. Because of individuality of each reference lamp, accurate knowledge of its spectrum between the (unfortunately) sparse major lines is important for precision radial velocimetry.
High sensitivity, wide coverage, and high-resolution NIR non-cryogenic spectrograph, WINERED
Author(s):
Yuji Ikeda;
Naoto Kobayashi;
Sohei Kondo;
Shogo Otsubo;
Satoshi Hamano;
Hiroaki Sameshima;
Tomoshiro Yoshikawa;
Kei Fukue;
Kenshi Nakanishi;
Takafumi Kawanishi;
Tetsuya Nakaoka;
Masaomi Kinoshita;
Ayaka Kitano;
Akira Asano;
Keiichi Takenaka;
Ayaka Watase;
Hiroyuki Mito;
Chikako Yasui;
Atsushi Minami;
Natsuko Izumu;
Ryo Yamamoto;
Misaki Mizumoto;
Takayuki Arasaki;
Akira Arai;
Noriyuki Matsunaga;
Hideyo Kawakita
Show Abstract
Near-infrared (NIR) high-resolution spectroscopy is a fundamental observational method in astronomy. It provides significant information on the kinematics, the magnetic fields, and the chemical abundances, of astronomical objects embedded in or behind the highly extinctive clouds or at the cosmological distances. Scientific requirements have accelerated the development of the technology required for NIR high resolution spectrographs using 10 m telescopes. WINERED is a near-infrared (NIR) high-resolution spectrograph that is currently mounted on the 1.3 m Araki telescope of the Koyama Astronomical Observatory in Kyoto-Sangyo University, Japan, and has been successfully operated for three years. It covers a wide wavelength range from 0.90 to 1.35 μm (the z-, Y-, and J-bands) with a spectral resolution of R = 28,000 (Wide-mode) and R = 80,000 (Hires-Y and Hires-J modes). WINERED has three distinctive features: (i) optics with no cold stop, (ii) wide spectral coverage, and (iii) high sensitivity. The first feature, originating from the Joyce proposal, was first achieved by WINERED, with a short cutoff infrared array, cold baffles, and custom-made thermal blocking filters, and resulted in reducing the time for development, alignment, and maintenance, as well as the total cost. The second feature is realized with the spectral coverage of Δλ/λ~1/6 in a single exposure. This wide coverage is realized by a combination of a decent optical design with a cross-dispersed echelle and a large format array (2k x 2k HAWAII- 2RG). The Third feature, high sensitivity, is achieved via the high-throughput optics (>60 %) and the very low noise of the system. The major factors affecting the high throughput are the echelle grating and the VPH cross-disperser with high diffraction efficiencies of ~83 % and ~86 %, respectively, and the high QE of HAWAII-2RG (83 % at 1.23 μm). The readout noise of the electronics and the ambient thermal background radiation at longer wavelengths could be major noise sources. The readout noise is 5.3 e- for NDR = 32, and the ambient thermal background is significantly reduced to ~ 0.05 e- pix-1 sec-1 at 273 K. As a result, the limiting magnitudes of WINERED are estimated to be mJ = 13.8 mag for the 1.3 m telescope, mJ = 16.9 mag for the 3.6 m telescope, and mJ = 19.2 mag for 10 m telescope with adoptive optics, respectively. Finally, we introduce some scientific highlights provided by WINERED for both emission and absorption line objects in the fields of stars, the interstellar medium, and the solar system.
Thermal stability improvements to the ESPaDOnS spectrograph with the addition of a thermal enclosure
Author(s):
Gregory Barrick;
Tom Benedict;
Claire Moutou;
Lison Malo;
John White;
André-Nicolas Chene;
Michael Lundquist
Show Abstract
As part of GRACES (Gemini Remote Access to CFHT ESPaDOnS Spectrograph), a project to link the Gemini-North telescope to the ESPaDOnS (Echelle Polarimetric Device for the Observation of Stars) spectrograph at CFHT (Canada- France-Hawaii Telescope), the original thermal enclosure of the spectrograph needed to be modified. Although the modifications were slight, there was a significant possibility that the thermal stability of ESPaDOnS would be somewhat compromised. To eliminate this risk, a walk-in thermal enclosure was purchased and installed around the ESPaDOnS spectrograph as part of the GRACES project. The thermal impact of these modifications to the ESPaDOnS environment will be analyzed and the effect of the changes on the amplitude and behavior of the spectral drift for the ESPaDOnS and GRACES instruments will be examined. While the outer enclosure has reduced the extremes in thermal variation, this has not had a direct effect on the stability of the spectra.
Performance characteristics of two volume phase holographic grisms produced for the ESPRESSO spectrograph
Author(s):
James A. Arns
Show Abstract
The ESPRESSO spectrograph [1], a new addition to the European Southern Observatory’s (ESO) Very Large Telescope (VLT), requires two volume phase holographic (VPH) grisms, one blue and the other red, splitting the overall spectral range of the instrument to maximize throughput while achieving high resolution. The blue grism covers the spectral range from 375 nm to 520 nm with a dispersion of 0.88 degrees/nm at the central wavelength of 438 nm. The red grism operates from 535 nm to 780 nm with a dispersion of 0.47 degrees/nm at 654.8 nm. Both designs use a single input prism to enhance the dispersion of the grism assembly. The grisms are relatively large in size with a working aperture of 185 mm x 185 mm for the blue grism and 215 nm x 185 mm for the red grism respectively. This paper describes the specifications of the two grating types, gives the rigorous coupled wave analysis (RCWA) theoretical performances of diffraction efficiency for the production designs and presents the measured performances of each of the delivered grisms.
Multi-fiber coupling through a miniature lens system into the FOCES spectrograph
Author(s):
Hanna Kellermann;
Frank Grupp;
Anna Brucalassi;
Liang Wang;
Nils Baisert;
Florian Lang-Bardl;
Ulrich Hopp;
Ralf Bender
Show Abstract
We present a new fiber-based light injection system for the high resolution spectrograph FOCES (Fiber Optics Cassegrain Echelle Spectrograph)1 which will soon start operating at the Wendelstein Observatory. The new system consists of several components such as a 4-fiber assembly (for simultaneous calibration), a new miniature lens system to reimage the light leaving the fibers onto the slit, as well as a new slit mask. The whole concept is specifically designed to provide high-accuracy, long-term stability for accurate radial velocity measurements and stellar atmosphere analyses.
Relative stability of two laser frequency combs for routine operation on HARPS and FOCES
Author(s):
Rafael A. Probst;
Gaspare Lo Curto;
Gerardo Ávila;
Anna Brucalassi;
Bruno L. Canto Martins;
Izan de Castro Leão;
Massimiliano Esposito;
Jonay I. González Hernández;
Frank Grupp;
Theodor W. Hänsch;
Ronald Holzwarth;
Hanna Kellermann;
Florian Kerber;
Olaf Mandel;
Antonio Manescau ;
Luca Pasquini;
Eszter Pozna;
Rafael Rebolo;
José Renan de Medeiros;
Sebastian P. Stark;
Tilo Steinmetz;
Alejandro Suárez Mascareño;
Thomas Udem;
Josefina Urrutia;
Yuanjie Wu
Show Abstract
We report on the installation of a laser frequency comb (LFC) at the HARPS spectrograph, which we characterize relative to a second LFC that we had brought to HARPS for testing. This allowed us for the first time to probe the relative stability of two independent astronomical LFCs over an extended wavelength range. Both LFCs covered the spectral range of HARPS at least from 460 to 690 nm. After optimization of the fiber coupling to HARPS to suppress modal noise, a relative stability of the two LFCs in the low cm/s range was obtained. In combination with the results of our four earlier LFC test campaigns on HARPS, the available data now cover a time span of more than six years.
CARMENES: the VIS channel spectrograph in operation
Author(s):
W. Seifert;
W. Xu;
O. Stahl;
H. J. Hagen;
M. A. Sánchez Carrasco;
G. Veredas;
J. A. Caballero;
J. Guardia;
J. Helmling;
L. Hernandez;
A. Pérez-Calpena;
S. Tulloch;
A. Kaminski;
M. Zechmeister;
A. Quirrenbach;
P. J. Amado;
I. Ribas;
A. Reiners;
H. Mandel
Show Abstract
CARMENES is a fiber-fed high-resolution Echelle spectrograph for the Calar Alto 3.5m telescope. The instrument is built by a German-Spanish consortium under the lead of the Landessternwarte Heidelberg. The search for planets around M dwarfs with a radial velocity of 1 m/s is the main focus of the planned science. Two channels, one for the visible, another for the near-infrared, will allow observations in the complete wavelength range from 550 to 1700 nm. To ensure the stability, the instrument is working in vacuum in a thermally controlled environment. The VIS channel spectrograph is covering the visible wavelength range from 0.55 to 0.95 μm with a spectral resolution of R=93,400 in a thermally and pressure-wise very stable environment. The VIS channel spectrograph started science operation in January 2016. Here we present the opto-mechanical and system design of the channel with the focus on the (re-)integration phase at the observatory and the measured performance during the testing and commissioning periods, including the lessons learned.
An ultra-stable cryostat for the detectors of ESPRESSO
Author(s):
Jean Louis Lizon;
Olaf Iwert;
Sebastian Deiries;
Hans Decker;
Renate Hinterschuster;
Antonio Manescau;
Denis Megevand;
Eric Mueller;
Francesco Alfonso Pepe;
Marco Riva
Show Abstract
ESPRESSO The Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, is a super-stable Optical High Resolution Spectrograph for the combined coude focus of the VLT. It can be operated by either one of the UTs or collecting the light from up to 4 UTs simultaneously. Given the wide spectral range, the optical path is split into two channels, two large 90 mm x 90 mm CCDs are used to record the full spectrum. In order to achieve the extremely high stability, ESPRESSO has a fixed optical layout; no moving parts are foreseen inside the spectrograph to maximize the stability and repeatability of the instrument performance and to avoid any thermal load generated inside the spectrograph itself. The optical bench is placed in a vacuum vessel hosted in a three level enclosure system able to guarantee temperature stability of the order of 0.001 K and in a vacuum environment. We aim for a stability of the spectral line on the detector pixel matrix in the range of a few nanometers. The paper gives a detailed description of the cryostat with the flexible de-coupling of the Dewar between the vacuum vessel and optical bench. The design including the measures taken in order to provide an optimal thermal connection and a very accurate mechanical referencing of the large chip. We are going to describe the specific experiment which has been set-up in order to verify and physically measure the real stability of the detector “pixels” relative to the rest of the world. We will also present the results obtained with the similar setup measuring the stability of the HARPS detector (the precursor of ESPRESSO) and the preliminary results of the stability of the final ESPRESSO detector system.
The Leiden EXoplanet Instrument (LEXI): a high-contrast high-dispersion spectrograph
Author(s):
S. Y. Haffert;
M. J. Wilby;
C. U. Keller;
I. A. G. Snellen
Show Abstract
The Leiden EXoplanet Instrument (LEXI) will be the first instrument designed for high-contrast, high-dispersion integral field spectroscopy at optical wavelengths. High-contrast imaging (HCI) and high-dispersion spectroscopy (HDS) techniques are used to reach contrasts of 10-7. LEXI will be a bench-mounted, high dispersion integral field spectrograph that will record spectra in a small area around the star with high spatial resolution and high dynamic range. A prototype is being setup to The Leiden EXoplanet Instrument (LEXI) will be the first instrument designed for high-contrast, high-dispersion integral field spectroscopy at optical wavelengths. High-contrast imaging (HCI) and high-dispersion spectroscopy (HDS) techniques are used to reach contrasts of 10-7. LEXI will be a bench-mounted, high dispersion integral field spectrograph that will record spectra in a small area around the star with high spatial resolution and high dynamic range. A prototype is being setup to test the combination of HCI+HDS and its first light is expected in 2016.
A calibration unit for the near-infrared spectropolarimeter SPIRou
Author(s):
Isabelle Boisse;
Sandrine Perruchot;
François Bouchy;
François Dolon;
François Moreau;
Rico Sottile;
François Wildi
Show Abstract
SPIRou is a near-infrared spectropolarimeter and high precision radial velocity instrument, to be implemented at CFHT in end 2017. It focuses on the search for Earth-like planets around M dwarfs and on the study of stellar and planetary formation in the presence of stellar magnetic field. The calibration unit and the radial-velocity reference module are essential to the short- and long-term precision (1 m/s). We highlight the specificities in the calibration techniques compared to the spectrographs HARPS (at LaSilla, ESO) or SOPHIE (at OHP, France) due to the near-infrared wavelengths, the CMOS detectors, and the instrument design. We also describe the calibration unit architecture, design and production.
CARMENES: interlocks or the importance of process visualization and system diagnostics in complex astronomical instruments
Author(s):
J. Helmling;
K. Wagner;
L. Hernández Castaño;
D. Benítez;
J. Marín Molina;
J. I. Vico Linares;
F. Hernández Hernando;
J. F. López Salas;
H. Magán;
A. Pérez-Calpena;
J. A. Caballero;
W. Seifert;
A. Quirrenbach;
P. J. Amado;
I. Ribas;
A. Reiners
Show Abstract
With the steadily increasing complexity of scientific instruments, there is an ever-growing demand for improved control electronics. This is especially important for infrared instruments, where the challenging vacuum and cryogenic systems increase the demands on the overall control system. The control electronics must monitor and adjust many different subsystems in different locations, some mounted at the telescope and others placed inside the telescope building. To implement these different demands, a comprehensive Interlock system with process visualization and powerful diagnostics has been developed at the Calar Alto Observatory and the Zentrum für Astronomie Heidelberg (LS
GIANO and HARPS-N together: towards an Earth-mass detection instrument
Author(s):
A. Tozzi;
E. Oliva;
M. Iuzzolino;
L. Fini;
A. Puglisi;
M. Sozzi;
G. Falcini;
L. Carbonaro;
A. Ghedina;
L. Mercatelli;
U. Seemann;
R. Claudi
Show Abstract
This article describes the works we are doing for modifying the interface between the high resolution infrared spectrograph GIANO (0.97-2.4 micron) and the TNG telescope, passing from a fiber feed configuration to the original design of a direct light-feeding from the telescope to the spectrograph. So doing the IR spectrograph, GIANO, will work in parallel to HARPS-N spectrometer (0.38-0.70 micron), the visible high resolution spectrograph, thanks to a new telescope interface based on a dichroic window that simultaneously feeds the two instrumentes: this is GIARPS (GIAno and haRPS). The scientific aims of this project are to improve the radial velocity accuracy achievable with GIANO, down to a goal of 1 m/s, the value necessary to detect Earth-mass planets on habitable orbits around late-M stars, to implement simultaneous observations with Harps-N and GIANO optimizing the study of planets around cool stars. The very broad wavelengths range is particularly important to discriminate false radial velocity signals caused by stellar activity. We therefore include several absorption cells with different mixtures of gases and a stabilized Fabry Perot cavity, necessary to have absorption lines over the 0.97–2.4 microns range covered by GIANO. The commissioning of GIARPS is scheduled by the end of 2016.
Achieving the resolution of the spectrograph of the 6m large Azimuthal telescope
Author(s):
Dmitrii Sazonenko;
Dmitrii Kukushkin;
Alexey Bakholdin;
Gennady Valyavin
Show Abstract
Special Astrophysical Observatory of Russian Academy of Sciences (SAO RAS) creates a spectrograph with high spectral resolution for the 6-meter telescope. The spectrograph consists of a mobile unit located at the focus of the telescope’s main mirror, a stationary part located under the telescope and optical fibers which transmit light from the mobile part to the stationary one. The spectral resolution of the stationary part should be R=100000. To achieve such a value, the scheme has two spectral elements, with cross-dispersion. The main spectral element is an echelle grating. The second spectral element is a prism with a diffraction grating on one facet.
HARPS3 for a roboticized Isaac Newton Telescope
Author(s):
Samantha J. Thompson;
Didier Queloz;
Isabelle Baraffe;
Martyn Brake;
Andrey Dolgopolov;
Martin Fisher;
Michel Fleury;
Joost Geelhoed;
Richard Hall;
Jonay I. González Hernández;
Rik ter Horst;
Jan Kragt;
Ramón Navarro;
Tim Naylor;
Francesco Pepe;
Nikolai Piskunov;
Rafael Rebolo;
Louis Sander;
Damien Ségransan;
Eugene Seneta;
David Sing;
Ignas Snellen;
Frans Snik;
Julien Spronck;
Eric Stempels;
Xiaowei Sun;
Samuel Santana Tschudi;
John Young
Show Abstract
We present a description of a new instrument development, HARPS3, planned to be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018. HARPS3 will be a high resolution (R≃115,000) echelle spectrograph with a wavelength range from 380-690 nm. It is being built as part of the Terra Hunting Experiment - a future 10- year radial velocity measurement programme to discover Earth-like exoplanets. The instrument design is based on the successful HARPS spectrograph on the 3.6m ESO telescope and HARPS-N on the TNG telescope. The main changes to the design in HARPS3 will be: a customised fibre adapter at the Cassegrain focus providing a stabilised beam feed and on-sky fibre diameter ≈1:4 arcsec, the implementation of a new continuous ow cryostat to keep the CCD temperature very stable, detailed characterisation of the HARPS3 CCD to map the effective pixel positions and thus provide an improved accuracy wavelength solution, an optimised integrated polarimeter and the instrument integrated into a robotic operation. The robotic operation will optimise our programme which requires our target stars to be measured on a nightly basis. We present an overview of the entire project, including a description of our anticipated robotic operation.
On-sky Doppler performance of TOU optical very high-resolution spectrograph for detecting low-mass planets
Author(s):
Jian Ge;
Bo Ma;
Sirinrat Sithajan;
Michael A. Singer;
Scott Powell;
Frank Varosi;
Bo Zhao;
Sidney Schofield;
Jian Liu;
Nolan Grieves;
Anthony Cassette;
Louis Avner;
Hali Jakeman;
Matthew Muterspaugh;
Michael Williamson;
Rory Barnes
Show Abstract
The TOU robotic, compact very high resolution optical spectrograph (R=100,000, 0.38-0.9 microns) has been fully characterized at the 2 meter Automatic Spectroscopy Telescope (AST) at Fairborn Observatory in Arizona during its pilot survey of 12 bright FGK dwarfs in 2015. This instrument has delivered sub m/s Doppler precision for bright reference stars (e.g., 0.7 m/s for Tau Ceti over 60 days) with 5-30 min exposures and 0.7 m/s long-term instrument stability, which is the best performance among all of the known Doppler spectrographs to our knowledge. This performance was achieved by maintaining the instrument in a very high vacuum of 1 micron torr and about 0.5 mK (RMS) long-term temperature stability through an innovative close-loop instrument bench temperature control. It has discovered a 21 Earth-mass planet (P=43days) around a bright K dwarf and confirmed three super-Earth planetary systems, HD 1461, 190360 and HD 219314. This instrument will be used to conduct the Dharma Planet Survey (DPS) in 2016-2019 to monitor ~100 nearby very bright FGK dwarfs (most of them brighter than V=8) at the dedicated 50-inch Robotic Telescope on Mt. Lemmon. With very high RV precision and high cadence (~100 observations per target randomly spread over 450 days), a large number of rocky planets, including possible habitable ones, are expected to be detected. The survey also provides the largest single homogenous high precision RV sample of nearby stars for studying low mass planet populations and constraining various planet formation models. Instrument on-sky performance is summarized.
Optical design of the NASA-NSF extreme precision Doppler spectrograph concept "WISDOM"
Author(s):
Stuart I. Barnes;
Gábor Fűrész;
Robert A. Simcoe;
Stephen A. Shectman;
Deborah F. Woods
Show Abstract
The WISDOM instrument concept was developed at MIT as part of a NASA-NSF funded study to equip the 3.5m WIYN telescope with an extremely precise radial velocity spectrometer. The spectrograph employs an asymmetric white pupil optical design, where the instrument is split into two nearly identical “Short” (380 to 750 nm) and “Long”" (750 to 1300 nm) wavelength channels. The echelle grating and beam sizes are R3.75/125mm and R6/80mm in the short and long channels respectively. Together with the pupil slicer, and octagonal to rectangular fibre coupling, this permits resolving powers over R = 120k with a 1.2” diameter fibre on the sky. A factor of two reduction in the focal length between the main collimator OAP and the transfer collimator ensures a very compact instrument, with a small white pupil footprint, thereby enabling small cross-dispersing and camera elements. A dichroic is used near the white pupil to split each of the long and short channels into two, so that the final spectrograph has 4 channels; namely “Blue,” “Green,” “Red” and “NIR.” Each of these channels has an anamorphic VPH grism for cross-dispersion, and a fully dioptric all-spherical camera objective. The spectral footprints cover 4k×4k and 6k×6k CCDs with 15 µm pixels in the short “Blue” and “Green” wavelength channels, respectively. A 4k×4k CCD with 15 μm pixels is used in the long “Red” channel, with a HgCdTe 1.7 μm cutoff 4k×4k detector with 10um pixels is to be used in the long "NIR" channel. The white pupil relay includes a Mangin mirror very close to the intermediate focus to correct the white pupil relay Petzval curvature before it is swept into a cylinder by the cross-dispersers. This design decision allows each of the dioptric cameras to be fully optimised and tested independently of the rest of the spectrograph. The baseline design for the cameras also ensures that the highest possible (diffraction limited) image quality is achieved across all wavelengths, while also ensuring insensitivity of spot centroid locations to variations in the pupil illumination. This insensitivity is proven to remain even in the presence of reasonable manufacturing and alignment tolerances. Fully ray-traced simulations of the spectral formats are used to demonstrate the optical performance, as well as to provide pre-first-light data that can be used to optimise the data reduction pipeline.
Performance and future developments of the RHEA single-mode spectrograph
Author(s):
Joao Bento;
Tobias Feger;
Michael J. Ireland;
Adam Rains;
Nemanja Jovanovic;
David W. Coutts;
Christian Schwab;
Alexander Arriola ;
Simon Gross
Show Abstract
The Replicable High-resolution Exoplanet and Asteroseismology (RHEA) spectrograph is being developed to serve as a basis for multiple copies across a network of small robotic telescopes. The spectrograph operates at the diffraction-limit by using a single-mode fiber input, resulting in a compact and modal-noise-free unit. The optical design is mainly based on off-the-shelf available components and comprises a near-Littrow configuration with prism cross-disperser. The échelle format covers a wavelength range of 430-650 nm at R=75,000 resolving power. In this paper we briefly summarize the current status of the instrument and present preliminary results from the first on-sky demonstration of the prototype using a fully automated 16" telescope, where we observe stable and semi-variable stars up to V=3.5 magnitude. Future steps to enhance the efficiency and passive stability of RHEA are discussed in detail. For example, we show the concept of using a multi-fiber injection unit, akin to a photonic lantern, which not only enables increased throughput but also offers simultaneous wavelength calibration.
NEWS: the near-infrared Echelle for wideband spectroscopy
Author(s):
Mark J. Veyette;
Philip S. Muirhead;
Zachary J. Hall;
Brian Taylor;
Jimmy Ye
Show Abstract
We present an updated optical and mechanical design of NEWS: the Near-infrared Echelle for Wide-band Spectroscopy (formerly called HiJaK: the High-resolution J, H and K spectrometer), a compact, high-resolution, near-infrared spectrometer for 5-meter class telescopes. NEWS provides a spectral resolution of 60,000 and covers the full 0.8-2.5 μm range in 5 modes. We adopt a compact, lightweight, monolithic design and have developed NEWS to be mounted to the instrument cube at the Cassegrain focus of the new 4.3-meter Discovery Channel Telescope.
Commissioning the dual etalon Fabry-Perot modes of the Robert Stobie spectrograph on the Southern African Large Telescope
Author(s):
T. B. Williams;
E. Romero-Colmenero;
P. Vaisanen;
K. Browne;
T. Makananise;
A. Koeslag;
C. Hettlage;
E. Wiid;
E. Simon;
M. P. Smith;
C. Pietraszewski
Show Abstract
The Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT) includes a Fabry-Pérot system that provides spectroscopic imaging over the 8 arcmin diameter science field of view, covering the wavelength range 430-860 nm with spectral resolutions ranging from 300 to10000 in four resolution modes. The higher resolution modes require the simultaneous use of two etalons. We discuss the complications encountered in implementing the dual etalon modes, the mechanical and operational solutions that have been devised, and the first science verification results. We also describe an efficient method for adjusting the parallelism of etalons in situ, and the use of the dual etalon system to determine the transmission of the individual etalons. The new dual etalon system was commissioned in late 2015 and is now producing useful scientific observations.
A high-resolution spectrograph for the 72cm Waltz Telescope at Landessternwarte, Heidelberg
Author(s):
M. Tala ;
P. Heeren;
M. Grill;
R. J. Harris;
J. Stürmer;
C. Schwab;
T. Gutcke;
S. Reffert;
A. Quirrenbach;
W. Seifert;
H. Mandel;
L. Geuer;
L. Schäffner;
G. Thimm;
U. Seeman;
J. Tietz;
K. Wagner
Show Abstract
The Waltz Spectrograph is a fiber-fed high-resolution échelle spectrograph for the 72 cm Waltz Telescope at the Landessternwarte, Heidelberg. It uses a 31.6 lines/mm 63.5° blaze angle échelle grating in white-pupil configuration, providing a spectral resolving power of R ~ 65,000 covering the spectral range between 450-800nm in one CCD exposure. A prism is used for cross-dispersion of échelle orders. The spectrum is focused by a commercial apochromat onto a 2k×2k CCD detector with 13.5μm per pixel. An exposure meter will be used to obtain precise photon-weighted midpoints of observations, which will be used in the computation of the barycentric corrections of measured radial velocities. A stabilized, newly designed iodine cell is employed for measuring radial velocities with high precision. Our goal is to reach a radial velocity precision of better than 5 m/s, providing an instrument with sufficient precision and sensitivity for the discovery of giant exoplanets. Here we describe the design of the Waltz spectrograph and early on-sky results.
A comprehensive radial velocity error budget for next generation Doppler spectrometers
Author(s):
Samuel Halverson;
Ryan Terrien;
Suvrath Mahadevan;
Arpita Roy;
Chad Bender;
Gudmundur Kári Stefánsson;
Andrew Monson;
Eric Levi;
Fred Hearty;
Cullen Blake;
Michael McElwain;
Christian Schwab;
Lawrence Ramsey;
Jason Wright;
Sharon Wang;
Qian Gong;
Paul Roberston
Show Abstract
We describe a detailed radial velocity error budget for the NASA-NSF Extreme Precision Doppler Spectrometer instrument concept NEID (NN-explore Exoplanet Investigations with Doppler spectroscopy). Such an instrument performance budget is a necessity for both identifying the variety of noise sources currently limiting Doppler measurements, and estimating the achievable performance of next generation exoplanet hunting Doppler spectrometers. For these instruments, no single source of instrumental error is expected to set the overall measurement floor. Rather, the overall instrumental measurement precision is set by the contribution of many individual error sources. We use a combination of numerical simulations, educated estimates based on published materials, extrapolations of physical models, results from laboratory measurements of spectroscopic subsystems, and informed upper limits for a variety of error sources to identify likely sources of systematic error and construct our global instrument performance error budget. While natively focused on the performance of the NEID instrument, this modular performance budget is immediately adaptable to a number of current and future instruments. Such an approach is an important step in charting a path towards improving Doppler measurement precisions to the levels necessary for discovering Earth-like planets.
Precision velocimetry planet hunting with PARAS: current performance and lessons to inform future extreme precision radial velocity instruments
Author(s):
Arpita Roy;
Abhijit Chakraborty;
Suvrath Mahadevan;
Priyanka Chaturvedi;
Neelam J.S.S.V. Prasad;
Vishal Shah;
F. M. Pathan;
B. G. Anandarao
Show Abstract
The PRL Advanced Radial-velocity Abu-sky Search (PARAS) instrument is a fiber-fed stabilized high-resolution cross-dispersed echelle spectrograph, located on the 1.2 m telescope in Mt. Abu India. Designed for exoplanet detection, PARAS is capable of single-shot spectral coverage of 3800 - 9600 Å, and currently achieving radial velocity (RV) precisions approaching ~1 m s-1 over several months using simultaneous ThAr calibration. As such, it is one of the few dedicated stabilized fiber-fed spectrographs on small (1-2 m) telescopes that are able to fill an important niche in RV follow-up and stellar characterization. The success of ground-based RV surveys is motivating the push into extreme precisions, with goals of ~ 10 cm s-1 in the optical and <1 m s-1 in the near-infrared (NIR). Lessons from existing instruments like PARAS are invaluable in informing hardware design, providing pipeline prototypes, and guiding scientific surveys. Here we present our current precision estimates of PARAS based on observations of bright RV standard stars, and describe the evolution of the data reduction and RV analysis pipeline as instrument characterization progresses and we gather longer baselines of data. Secondly, we discuss how our experience with PARAS is a critical component in the development of future cutting edge instruments like (1) the Habitable Zone Planet Finder (HPF), a near-infrared spectrograph optimized to look for planets around M dwarfs, scheduled to be commissioned on the Hobby Eberly Telescope in 2017, and (2) the NEID optical spectrograph, designed in response to the NN-EXPLORE call for an extreme precision Doppler spectrometer (EPDS) for the WIYN telescope. In anticipation of instruments like TESS and GAIA, the ground-based RV support system is being reinforced. We emphasize that instruments like PARAS will play an intrinsic role in providing both complementary follow-up and battlefront experience for these next generation of precision velocimeters.
EXPRES: a next generation RV spectrograph in the search for earth-like worlds
Author(s):
C. Jurgenson;
D. Fischer;
T. McCracken;
D. Sawyer;
A. Szymkowiak;
A. Davis;
G. Muller;
F. Santoro
Show Abstract
The EXtreme PREcision Spectrograph (EXPRES) is an optical fiber fed echelle instrument being designed and built at the Yale Exoplanet Laboratory to be installed on the 4.3-meter Discovery Channel Telescope operated by Lowell Observatory. The primary science driver for EXPRES is to detect Earth-like worlds around Sun-like stars. With this in mind, we are designing the spectrograph to have an instrumental precision of 15 cm/s so that the on-sky measurement precision (that includes modeling for RV noise from the star) can reach to better than 30 cm/s. This goal places challenging requirements on every aspect of the instrument development, including optomechanical design, environmental control, image stabilization, wavelength calibration, and data analysis. In this paper we describe our error budget, and instrument optomechanical design.
NRES: the network of robotic Echelle spectrographs
Author(s):
Robert J. Siverd;
Timothy M. Brown;
John Hygelund;
Todd Henderson;
Joseph R. Tufts;
Jason D. Eastman;
Julian van Eyken;
Stuart Barnes
Show Abstract
Las Cumbres Observatory Global Network (LCOGT) is building the Network of Robotic Echelle Spectrographs (NRES), which will consist of six identical, optical (390 - 860 nm) high-precision spectrographs, each fiber-fed simultaneously by up to two 1-meter telescopes and a thorium argon calibration source. We plan to install one at up to 6 observatory sites in the Northern and Southern hemispheres, creating a single, globally-distributed, autonomous spectrograph facility using up to twelve 1-meter telescopes. Simulations suggest we will achieve long-term radial velocity precision of 3 m/s in less than an hour for stars brighter than V = 12. We have been funded with NSF MRI and ATI grants, and expect our first spectrograph to be deployed in fall 2016, with the full network operation of 5 or 6 units beginning in 2017. We will briefly overview the NRES design, goals, robotic operation, and status. In addition, we will discuss early results from our prototype spectrograph, the laboratory and on-sky performance of our first production unit, and the ongoing software development effort to bring this resource online.
Spectrograph sensitivity analysis: an efficient tool for different design phases
Author(s):
M. Genoni;
M. Riva;
G. Pariani;
M. Aliverti;
M. Moschetti
Show Abstract
In this paper we present an efficient tool developed to perform opto-mechanical tolerance and sensitivity analysis both for the preliminary and final design phases of a spectrograph. With this tool it will be possible to evaluate the effect of mechanical perturbation of each single spectrograph optical element in terms of image stability, i.e. the motion of the echellogram on the spectrograph focal plane, and of image quality, i.e. the spot size of the different echellogram wavelengths. We present the MATLAB-Zemax script architecture of the tool. In addition we present the detailed results concerning its application to the sensitivity analysis of the ESPRESSO spectrograph (the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations which will be soon installed on ESO’s Very Large Telescope) in the framework of the incoming assembly, alignment and integration phases.
KPF: Keck Planet Finder
Author(s):
Steven R. Gibson;
Andrew W. Howard;
Geoffrey W. Marcy;
Jerry Edelstein;
Edward H. Wishnow;
Claire L. Poppett
Show Abstract
KPF is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. The instrument is designed to characterize exoplanets via Doppler spectroscopy with a single measurement precision of 0.5ms-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. KPF will have a 200mm collimated beam diameter and a resolving power of >80,000. The design includes a green channel (440nm to 590 nm) and red channel (590nm to 850 nm). A novel design aspect of KPF is the use of a Zerodur optical bench, and Zerodur optics with integral mounts, to provide stability against thermal expansion and contraction effects.
MMP, the Multi Mini Prism device for ESPRESSO APSU: prototyping and integration
Author(s):
Luca Oggioni;
G. Pariani;
M. Moschetti;
M. Riva;
M. Genoni;
M. Aliverti;
M. Landoni
Show Abstract
slicer, is necessary to differently fold each field to correctly illuminate the echelle and this is made by cylindrical prisms glued onto a silica window. We present the integrated robotic system conceived to reach the required tolerances in term of alignment and integration. It consists in a tip/tilt stage to select the wedge angle, a rotational stage to select the right clock angle, coupled to an x-y stage to position the elements on the window and a z axis to perform the gluing.
The iLocater cryostat: design and thermal control strategy for precision radial velocity measurements
Author(s):
Jonathan Crass;
Louis G. Fantano;
Frederick R. Hearty;
Justin R. Crepp;
Matthew J. Nelson;
Sheila M. Wall;
David A. Cavalieri;
Corina Koca;
David L. King;
Robert O. Reynolds;
Karl R. Stapelfeldt
Show Abstract
The current generation of precision radial velocity (RV) spectrographs are seeing-limited instruments. In order to achieve high spectral resolution on 8m class telescopes, these spectrographs require large optics and in turn, large instrument volumes. Achieving milli-Kelvin thermal stability for these systems is challenging but is vital in order to obtain a single measurement RV precision of better than 1m/s. This precision is crucial to study Earth-like exoplanets within the habitable zone. iLocater is a next generation RV instrument being developed for the Large Binocular Telescope (LBT). Unlike seeinglimited RV instruments, iLocater uses adaptive optics (AO) to inject a diffraction-limited beam into single-mode fibers. These fibers illuminate the instrument spectrograph, facilitating a diffraction-limited design and a small instrument volume compared to present-day instruments. This enables intrinsic instrument stability and facilitates precision thermal control. We present the current design of the iLocater cryostat which houses the instrument spectrograph and the strategy for its thermal control. The spectrograph is situated within a pair of radiation shields mounted inside an MLI lined vacuum chamber. The outer radiation shield is actively controlled to maintain instrument stability at the sub-mK level and minimize effects of thermal changes from the external environment. An inner shield passively dampens any residual temperature fluctuations and is radiatively coupled to the optical board. To provide intrinsic stability, the optical board and optic mounts will be made from Invar and cooled to 58K to benefit from a zero coefficient of thermal expansion (CTE) value at this temperature. Combined, the small footprint of the instrument spectrograph, the use of Invar, and precision thermal control will allow long-term sub-milliKelvin stability to facilitate precision RV measurements.
VINROUGE: a very compact 2-5um high-resolution spectrograph with germanium immersion grating
Author(s):
Takayuki Arasaki;
Naoto Kobayashi;
Yuji Ikeda;
Shohei Kondo;
Yuki Sarugaku;
Sayumi Kaji;
Hideyo Kawakita
Show Abstract
The infrared high-resolution and highly-sensitive spectroscopy can provide new and deep insights in many fields of astronomy. The 2.0-5.5 μm region is a very unique and important wavelength region for astrochemistry and astrobiology, because the vibrational transitions of C-H, N-H, O-H, C-O, and C-N bonds in many molecules, which are of astrophysical interest, concentrate in this wavelength range. To advance the study in this wavelength range, we are developing a new near-infrared spectrograph: VINROUGE (= Very-compact INfrared high-ResOlUtion Ge-immersion Echelle spectrograph). The instrumental concepts of VINROUGE are “high-resolution”, “highly-sensitive”, and “very-compact instrumentation”. With (i) Germanium immersion grating, (ii) white pupil spectrograph design, (iii) reflective optics using the integrated off-axis mirrors and the optical bench by ceramic (cordierite CO-220), and (iv) highly-sensitive array (HAWAII-2RG 5.3μm cutoff array), we could obtain a solution of optical design with a spectral resolution of 80,000, total throughput of > 0.28, and a compact volume that is smaller than 600 mm×600 mm×600 mm even for 10-m class telescope. We have already completed the development of Germanium immersion grating. In this year, we plan to fabricate a set of integrated off-axis ceramic mirrors together with the ceramic optical bench to demonstrate that the reflective optics was an athermal performance. The first light of VINROUGE is expected in 2019.
Precision single mode fibre integral field spectroscopy with the RHEA spectrograph
Author(s):
Adam D. Rains;
Michael J. Ireland;
Nemanja Jovanovic;
Tobias Feger;
Joao Bento;
Christian Schwab;
David W. Coutts;
Olivier Guyon;
Alexander Arriola;
Simon Gross
Show Abstract
The RHEA Spectrograph is a single-mode echelle spectrograph designed to be a replicable and cost effective method of undertaking precision radial velocity measurements. Two versions of RHEA currently exist, one located at the Australian National University in Canberra, Australia (450 - 600nm wavelength range), and another located at the Subaru Telescope in Hawaii, USA (600 - 800 nm wavelength range). Both instruments have a novel fibre feed consisting of an integral field unit injecting light into a 2D grid of single mode fibres. This grid of fibres is then reformatted into a 1D array at the input of the spectrograph (consisting of the science fibres and a reference fibre capable of receiving a white-light or xenon reference source for simultaneous calibration). The use of single mode fibres frees RHEA from the issue of modal noise and significantly reduces the size of the optics used. In addition to increasing the overall light throughput of the system, the integral field unit allows for cutting edge science goals to be achieved when operating behind the 8.2m Subaru Telescope and the SCExAO adaptive optics system. These include, but are not limited to: resolved stellar photospheres; resolved protoplanetary disk structures; resolved Mira shocks, dust and winds; and sub-arcsecond companions. We present details and results of early tests of RHEA@Subaru and progress towards the stated science goals.
First high-efficiency and high-resolution (R=80,000) NIR spectroscopy with high-blazed Echelle grating: WINERED HIRES modes
Author(s):
Shogo Otsubo;
Yuji Ikeda;
Naoto Kobayashi;
Takashi Sukegawa;
Sohei Kondo;
Satoshi Hamano;
Hiroaki Sameshima;
Kei Fukue;
Tomohiro Yoshikawa;
Kenshi Nakanishi;
Ayaka Watase;
Keiichi Takenaka;
Akira Asano;
Chikako Yasui;
Noriyuki Matsunaga;
Hideyo Kawakita
Show Abstract
WINERED is a PI-type 0.9 – 1.35 μm high-resolution spectrograph developed by the Laboratory of Infrared highresolution Spectrograph (LiH) of the Koyama Astronomical Observatory at Kyoto Sangyo University, Japan. The scope of WINERED is to realize a high-resolution near-infrared (NIR) spectrograph with both wide coverage and high sensitivity. WINERED provides three observational modes called as the Wide, Hires-Y and Hires-J modes. The Wide mode simultaneously covers the z, Y and J-bands in a single exposure with R ≡ λ/Δλ = 28,000 and was commissioned for the 1.3 m Araki Telescope of Koyama Astronomical Observatory in 2013. We have been building alternative observational modes “Hires-Y” and “Hires-J”, providing R = 80,000 spectra in the Y- and J-bands, respectively. There are two choices for realizing a compact spectrograph with a high spectral resolution of R ≧ 50,000: an immersion grating (IG) or a highblazed echelle grating (HBG). Investigating the availabilities of both optical devices, we selected an HBG solution for λ < 1.5 μm because can be realized with currently available technology in earlier time. The optical parameters of WINERED’s HBGs are as follows: groove pitch = 90.38 μm, blaze angle = 79.32 °, and apex angle = 88°, which are determined to minimize vignetting in the optical system as well as aberrations with the spectral resolution of R = 80,000. Custom HBGs were made by CANON Inc. Because of the size the size limitation in fabrication process, we decided to use a mosaicked grating consisting of two HBGs. The alignment tolerances of the two HBGs are very tight (< 0.5 arcsec for the parallelism between grooves of the two gratings and 1.5 arcsec for the flatness between the two grating surfaces). To enable these fine alignments, we designed a grating holder with an adjustment mechanism with sub-μm positional resolution. We adapted cordierite CO-220 as the material for the grating holder, thereby reducing the misalignment generated by thermal expansions/compression with extremely low coefficient of thermal expansion (CTE < 2.0 ×10−8 K-1 at 23 °C). As a result of the measurement of the two HBGs installed in the grating holder, we confirmed the parallelism of < 0.1 arcsec. Finally, we evaluated the total optical performances of the Hires modes with the HBGs. The widths of the monochromatic slitimages obtained with a Th-Ar lamp were measured to be 1.7 – 2.3 pixels, which agreed well with the designed values (1.6 – 2.6 pixels). These results should guarantee the spectral resolution (R = 78,000) estimated from the measurement of the linear dispersion [pix / μm]. Because there was an avoidable degradation in reducing the two-dimensional spectrum using HBGs with a large γ angle, the final spectral resolution of the reduced one-dimensional spectrum results in R = 68,000.
The precision radial velocity error budget for the Gemini High-resolution Optical SpecTrograph (GHOST)
Author(s):
Michael J. Ireland;
Étienne Artigau;
Greg Burley;
Michael Edgar;
Steve Margheim;
Gordon Robertson;
John Pazder;
Richard McDermid;
Ross Zhelem
Show Abstract
The Gemini High-resolution Optical SpecTrograph (GHOST) is a fiber fed spectrograph primarily designed for high efficiency and broad wavelength coverage (363 -1000nm), with an anticipated commissioning early in 2018. The primary scientific goal of the Precision Radial Velocity (PRV) mode will be follow-up of relatively faint (R>12) transiting exoplanet targets, especially from the TESS mission. In the PRV mode, the 1.2 arcsec diameter stellar image will be split 19 ways, combined in a single slit with a simultaneous Th/Xe reference source, dispersed at a resolving power of 80,000 and imaged onto two detectors. The spectrograph will be thermally stabilized in the Gemini pier laboratory, and modal noise will be reduced below other sources through the use of a fiber agitator. Unlike other precision high resolution spectrographs, GHOST will not be pressure controlled (although pressure will be monitored precisely), and there will be no double scrambler or shaped (e.g. octagonal) fibers. Instead, GHOST will have to rely on simultaneous two-color imaging of the slit and the simultaneous Th/Xe fiber to correct for variable fiber illumination and focal-ratio degradation. This configuration presents unique challenges in estimating a PRV error budget.
Integration, alignment, and verification of the ESPRESSO Front-End
Author(s):
G. Pariani;
M. Aliverti;
M. Moschetti;
M. Landoni;
M. Riva;
F. M. Zerbi;
D. Mégevand;
S. Cristiani;
F. Pepe
Show Abstract
ESPRESSO, Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, is now under the assembly, integration and verification phase and will be installed beginning next year at Paranal Observatory on ESO's Very Large Telescopes. The Front End is the modular system in the Combined Coudé Laboratory receiving the light from the four VLT Units, providing the needed connection between the input signal, i.e., object light, sky light, and calibration light, to feed the spectrograph through optical fibers. The modular concept of the FE Units drove the system design and the alignment workflow. We will show the integration method of the single FE modules adopted to guarantee the necessary repeatability between the different Units. The performances of the system in terms of image quality and encircled energy in the observed point spread function are reported. Finally, the strategy followed in the Paranal Combined Coudè Laboratory to define the convergence point of the four UTs is described, along with the procedure used to align the ground plates, the main structure, and the mode selector.
Integration and alignment through mechanical measurements: the example of the ESPRESSO front-end units
Author(s):
Matteo Aliverti;
Giorgio Pariani;
Manuele Moschetti;
Marco Riva
Show Abstract
Traditional techniques usually rely on optical feedback to align optical elements over all the degrees of freedom needed. This strongly iterative process implies the use of bulky and/or flexible adjustable mountings. Another solution under study consists in the characterization of every optomechanical elements and the integration of the parts without any optical feedback. The characterization can be performed using different 3D Coordinate Measuring Machines (like Laser Tracker, Articulated Arms and Cartesian ones) and referencing different parts like the optomechanical mounts or the optical surfaces. The alignment of the system is done adjusting the six degrees of freedom of every element with metallic shims. Those calibrated elements are used to correct the interfaces position of the semikinematic system composed by 3 screws and 3 pins. In this paper, the integration and alignment of the ESPRESSO Front End Units (FEUs) will be used as pathfinder to test different alignment methods and evaluate their performances.
The fiber noise suppression of astro-comb fiber link system for Chinese 2.16m telescope
Author(s):
Huiqi Ye;
Jian Han;
Yuanjie Wu;
Dong Xiao
Show Abstract
We built a fiber link system to connect the astronomical laser frequency combs (astro-comb) and the HRS spectrograph for Chinese 2.16m telescope in Xinglong. Fiber noise deteriorates the precision and stability of high spectral resolution fiber-fed spectrograph, especially when the astro-comb is used as calibrators. In order to optimize the performance of the astro-comb fiber link system, it is essential to suppress the fiber noise. The polygonal fiber is used to improve the scrambling and a vibrator attached to fiber is used to eliminate the speckle. The experiment results show good suppression of fiber noise with polygonal fiber, especially for the octagonal fiber, together with dynamic agitation by a vibrator.
The Gemini High-Resolution Optical SpecTrograph (GHOST) bench spectrograph optical design
Author(s):
John Pazder;
Greg Burley;
Michael J. Ireland;
Gordon Robertson;
Andrew Sheinis;
Ross Zhelem
Show Abstract
Gemini High-Resolution Optical SpecTrograph (GHOST) is a fiber-fed spectrograph being developed for the Gemini telescope. GHOST is a white pupil échelle spectrograph with high efficiency and a broad continuous wavelength coverage (363-1000nm) with R>50,000 in two-object mode and >75,000 in single-object mode. The design incorporates a novel zero-Petzval sum white pupil relay to eliminate grating aberrations at the cross-dispersers. Cameras are based on non-achromatic designs with tilted detectors to eliminate the need for exotic glasses. This paper outlines the optical design of the bench-mounted spectrograph and the predicted spectrograph resolution and efficiency for the spectrograph.
Fiber link design for the NASA-NSF extreme precision Doppler spectrograph concept "WISDOM"
Author(s):
Gábor Fűrész;
Rafal Pawluczyk;
Paul Fournier;
Robert Simcoe;
Deborah F. Woods
Show Abstract
We describe the design of the fiber-optic coupling and light transfer system of the WISDOM (WIYN Spectrograph for DOppler Monitoring) instrument. As a next-generation Precision Radial Velocity (PRV) spectrometer, WISDOM incorporates lessons learned from HARPS about thermal, pressure, and gravity control, but also takes new measures to stabilize the spectrograph illumination, a subject that has been overlooked until recently. While fiber optic links provide more even illumination than a conventional slit, careful engineering of the interface is required to realize their full potential. Conventional round fiber core geometries have been used successfully in conjunction with optical double scramblers, but such systems still retain a memory of the input illumination that is visible in systems seeking sub-m/s PRV precision. Noncircular fibers, along with advanced optical scramblers, and careful optimization of the spectrograph optical system itself are therefore necessary to study Earth-sized planets. For WISDOM, we have developed such a state-of-the-art fiber link concept. Its design is driven primarily by PRV requirements, but it also manages to preserve high overall throughput. Light from the telescope is coupled into a set of six, 32 μm diameter octagonal core fibers, as high resolution is achieved via pupil slicing. The low-OH, step index, fused silica, FBPI-type fibers are custom designed for their numerical aperture that matches the convergence of the feeding beam and thus minimizes focal ratio degradation at the output. Given the demanding environment at the telescope the fiber end tips are mounted in a custom fused silica holder, providing a perfect thermal match. We used a novel process, chemically assisted photo etching, to manufacture this glass fiber holder. A single ball-lens scrambler is inserted into the 25m long fibers. Employing an anti-reflection (AR) coated, high index, cubic-zirconia ball lens the alignment of the scrambler components are straightforward, as the fiber end tips (also AR coated) by design touch the ball lens and thus eliminate spacing tolerances. A clever and simple opto-mechanical design and assembly process assures micron-level self-alignment, yielding a ~87% throughput and a scrambling gain of >20,000. To mitigate modal noise the individual fibers then subsequently combined into a pair of rectangular fibers, providing a much larger modal area thanks to the 34x106 micron diameter. To minimize slit height, and thus better utilize detector area, the octagonal cores are brought very close together in this transition. The two outer fibers are side polished at one side, into a D-shaped cladding, while the central fiber has a dual side polish. These tapered, side-flattening operations are executed with precise alignment to the octagonal core. Thus the cores of the 3 fibers are brought together and aligned within few microns of each other before spliced onto the rectangular fiber. Overall throughput kept high and FRD at bay by careful management of fiber mounting, vacuum feed-through, application of efficient AR coatings, and implementation of thermal breaks that allow for independent expansion of the fibers and the protective tubing.
Design of NEID, an extreme precision Doppler spectrograph for WIYN
Author(s):
C. Schwab;
A. Rakich;
Q. Gong;
S. Mahadevan;
S. P. Halverson;
A. Roy;
R. C. Terrien;
P. M. Robertson;
F. R. Hearty;
E. I. Levi;
A. J. Monson;
J. T. Wright;
M. W. McElwain;
C. F. Bender;
C. H. Blake;
J. Stürmer;
Y. V. Gurevich;
A. Chakraborty;
L. W. Ramsey
Show Abstract
We have developed an optical design for a high resolution spectrograph in response to NASA’s call for an extreme precision Doppler spectrometer (EPDS) for the WIYN telescope. Our instrument covers a wavelength range of 380 to 930 nm using a single detector and with a resolution of 100,000. To deliver the most stable spectrum, we avoid the use of an image slicer, in favor of a large (195 mm diameter) beam footprint on a 1x2 mosaic R4 Echelle grating. The optical design is based on a classic white pupil layout, with a single parabolic mirror that is used as the main and transfer collimator. Cross dispersion is provided by a single large PBM2Y glass prism. The refractive camera consists of only four rotationally symmetric lenses made from i-Line glasses, yet delivers very high image quality over the full spectral bandpass. We present the optical design of the main spectrograph bench and discuss the design trade-offs and expected performance.
The HARPS-North@TNG polarimeter
Author(s):
Francesco Leone;
Massimo Cecconi;
Rosario Cosentino;
Adriano Ghedina;
Marina Giarrusso;
Marcos Hernandez Diaz;
Manuel Gonzalez;
Matteo Munari;
Héctor Pérez Ventura;
Luis Riverol;
José San Juan Gómez;
Salvatore Scuderi
Show Abstract
The Multi-AO Imaging Camera for Deep Observations (MICADO), a first light instrument for the 39 m European Extremely Large Telescope (E-ELT), is being designed and optimized to work with the Multi-Conjugate Adaptive Optics (MCAO) module MAORY (0.8-2.5 μm). The current concept of the MICADO instrument consists of a structural cryostat (2.1 m diameter and 2 m height) with the wavefront sensor (WFS) on top. The cryostat is mounted via its central flange with a direct interface to a large 2.5-m-diameter high-precision bearing, which rotates the entire camera (plus wavefront sensor) assembly to allow for image derotation without individually moving optical elements. The whole assembly is suspended at 3.6 m above the E-ELT Nasmyth platform by a Hexapod-type support structure. We describe the design of the MICADO derotator, a key mechanism that must precisely rotate the cryostat/SCAO-WFS assembly around its optical axis with an angular positioning accuracy better than 10 arcsec, in order to compensate the field rotation due to the alt-azimuth mount of the E-ELT. Special attention is being given to simulate the performance of the derotator during the design phase, in which both static and dynamics behaviors are being considered in parallel. The statics flexure analysis is done using a detailed Finite Element Model (FEM), while the dynamics simulation is being developed with the mathematical model of the derotator implemented in Matlab/Simulink. Finally, both aspects must be combined through a realistic end-to-end model. The experiment designed to prove the current concept of the MICADO derotator is also presented in this work.
First light of a laser frequency comb at SALT
Author(s):
Éric Depagne;
Richard A. McCracken;
Derryck T. Reid;
Rudi B. Kuhn;
Nicolas Erasmus;
Lisa A. Crause
Show Abstract
We present preliminary results of the commissioning and testing of SALT-CRISP (SALT-Calibration Ruler for Increased Spectrograph Precision), a Laser Frequency Comb (LFC) built by Heriot-Watt University and temporarily installed at the Southern African Large Telescope (SALT). The comb feeds the High Stability mode of SALT's High Resolution Spectrograph (HRS) and fully covers the wavelength range of the red channel of the HRS: 555-890 nm. The LFC provides significantly improved wavelength calibration compared to a standard Thorium-Argon (ThAr) lamp and hence offers unprecedented opportunities to characterise the resolution, stability and radial velocity precision of the HRS. Results from this field trial will be incorporated into subsequent LFC designs.
Optical design of MEMS-based infrared multi-object spectrograph concept for the Gemini South Telescope
Author(s):
Shaojie Chen;
Suresh Sivanandam;
Dae-Sik Moon
Show Abstract
We discuss the optical design of an infrared multi-object spectrograph (MOS) concept that is designed to take advantage of the multi-conjugate adaptive optics (MCAO) corrected field at the Gemini South telescope. This design employs a unique, cryogenic MEMS-based focal plane mask to select target objects for spectroscopy by utilizing the Micro-Shutter Array (MSA) technology originally developed for the Near Infrared Spectrometer (NIRSpec) of the James Webb Space Telescope (JWST). The optical design is based on all spherical refractive optics, which serves both imaging and spectroscopic modes across the wavelength range of 0.9−2.5 μm. The optical system consists of a reimaging system, MSA, collimator, volume phase holographic (VPH) grisms, and spectrograph camera optics. The VPH grisms, which are VPH gratings sandwiched between two prisms, provide high dispersing efficiencies, and a set of several VPH grisms provide the broad spectral coverage at high throughputs. The imaging mode is implemented by removing the MSA and the dispersing unit out of the beam. We optimize both the imaging and spectrographic modes simultaneously, while paying special attention to the performance of the pupil imaging at the cold stop. Our current design provides a 1' ♦ 1' and a 0.5' ♦ 1' field of views for imaging and spectroscopic modes, respectively, on a 2048 × 2048 pixel HAWAII-2RG detector array. The spectrograph’s slit width and spectral resolving power are 0.18'' and 3,000, respectively, and spectra of up to 100 objects can be obtained simultaneously. We present the overall results of simulated performance using optical model we designed.
Performance characteristics of a suite of volume phase holographic gratings produced for the Subaru prime focus spectrograph
Author(s):
James A. Arns
Show Abstract
The Subaru Prime Focus Spectrograph[1] (PFS) requires a suite of volume phase holographic (VPH) gratings that parse the observational spectrum into three sub-spectral regions. In addition, the red region has a second, higher resolution arm that includes a VPH grating that will eventually be incorporated into a grism. This paper describes the specifications of the four grating types, gives the theoretical performances of diffraction efficiency for the production designs and presents the measured performances on the gratings produced to date.
The Dark Energy Spectroscopic Instrument (DESI) instrument mechanism control systems
Author(s):
Carl T. Coker;
Daniel Pappalardo;
Richard Pogge;
Paul Martini;
Mark Derwent;
Thomas P. O'Brien;
Klaus Honscheid
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5,000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We present the design details of the instrument mechanism control systems for the spectrographs. Each spectrograph has a stand-alone mechanism control box that operates the unit's four remotely-operated mechanisms (two shutters and two Hartmannn doors), and provides a suite of temperature and humidity sensors. Each control box is highly modular, and is operated by a dedicated on-board Linux computer to provide all of the control and monitoring functions. We describe our solution for integrating a number of network-connected devices within each unit spectrograph, and describe the basic software architecture.
Fusion splicing: a novel approach to fiber connections for the Dark Energy Spectroscopic Instrument
Author(s):
Parker Fagrelius;
Claire Poppett;
Jerry Edelstein
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the Baryon Acoustic Oscillation (BAO) technique and the growth of structure using redshift-space distortions (RSD). The spectra of 40 million galaxies over 14,000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers will run 50 meters from the focal plane to the coud´e room where they feed ten broadband spectrographs. The focal plane assembly will be integrated separately from the spectrograph slits and long fiber cables in order to ease integration flow, and the two subsystems will be connected before final integration on the telescope. In order to retain maximum throughput and minimize the focal ratio degradation (FRD) when connecting the fiber system, we are employing fusion splicing as opposed to mechanical connectorization. For the best splice performance, the optical fibers are stripped of their polyimide coating, precision cleaved, and then fused with a heating filament. We report results from the splicing process, measuring a collimated FRD increase of less than 0.5 degrees for a f/3.9 input beam compared to >1 degree increase for mechanical connectors. We also show that the near field performance is minimally degraded after splicing. These results represent the first of their kind for a fiber-fed astronomical instrument.
Toward the final optical design MOONS, the Multi-Object Optical and Near infrared Spectrometer for the VLT
Author(s):
E. Oliva;
B. Delabre;
A. Tozzi;
D. Ferruzzi;
D. Lee;
I. Parry;
P. Rees II
Show Abstract
MOONS (Multi-Object Optical and Near-infrared Spectrograph for the VLT) is entering into the final design phase. This paper presents and discusses the latest proposed version of the optical design of the cryogenic spectrograph. The main developments and modifications were aimed at minimizing the overall size and mass of the cryogenic spectrograph. The most remarkable new feature is the design of an extremely fast (F/0.95), light and compact (40 kg in less than 80 dm3) camera with superb image quality over a very large field of view (9 degrees on a collimated beam of 265 mm). The camera consists of only three optical elements: two lenses and one mirror. All elements are made of fused-silica. The optical performances are independent on the temperature, i.e. the camera can be fully characterized at room temperatures.
The DESI shutter with integrated fiber illumination system
Author(s):
Mark A. Derwent;
Thomas P. O'Brien;
Daniel P. Pappalardo;
Paul Martini;
Carl T. Coker;
Richard W. Pogge
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe the unique shutter design that incorporates a fiber illumination system into the shutter blade. When activated, the fiber illumination system directs intense 430-480nm wavelength light at the instrument’s fiber slit in order to back-illuminate the telescope’s focal plane and verify the location of the robotic fiber positioners. The back-illumination is typically active during science exposure read-outs and therefore requires the shutter to attenuate light by a factor of at least 107. This paper describes how we have integrated the fiber illumination system into the shutter blade, as well as incorporated an inflatable seal around the shutter aperture to achieve the light attenuation requirement. We also present lab results that characterize the fiber illumination and shutter attenuation. Finally, we discuss the control scheme that executes exposure and fiber illumination modes, and meets the shutter timing requirements.
Developments in fiber-positioning technology for the WEAVE instrument at the William Herschel Telescope
Author(s):
Ellen Schallig;
Ian J. Lewis;
James Gilbert;
Gavin Dalton;
Matthew Brock;
Don Carlos Abrams;
Kevin Middleton;
J. Alfonso L. Aguerri;
Piercarlo Bonifacio;
Esperanza Carrasco ;
Scott C. Trager;
Antonella Vallenari
Show Abstract
WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) on La Palma in the Canary Islands, Spain. It is a multi-object "pick-and-place" fibre-fed spectrograph with a 1000 fibre multiplex behind a new dedicated 2° prime focus corrector. The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction). In this paper we describe some of the final design decisions arising from the prototyping phase of the instrument design and provide an update on the current manufacturing status of the fibre positioner system.
4MOST low-resolution spectrograph: design and performances
Author(s):
F. Laurent;
Johan Kosmalski;
Didier Boudon;
Patrick Caillier;
Eric Daguisé;
Jean-Emmanuel Migniau;
Arlette Pécontal;
Johan Richard;
Samuel C. Barden;
Olga Bellido-Tirado;
Steffen Frey;
Allar Saviauk
Show Abstract
4MOST, the 4m Multi Object Spectroscopic Telescope, is an upcoming optical, fibre-fed, MOS facility for the VISTA telescope at ESO's Paranal Observatory in Chile. Its main science drivers are in the fields of galactic archeology, highenergy physics, galaxy evolution and cosmology. The preliminary design of 4MOST features 2436 fibres split into lowresolution (1624 fibres, 370-950 nm, R > 4000) and high-resolution spectrographs (812 fibres, three arms, ~44-69 nm coverage each, R >18000) with a fibre positioner and covering an hexagonal field of view of ~4.1 deg2. The 4MOST consortium consists of several institutes in Europe and Australia under leadership of the Leibniz-Institut für Astrophysik, Potsdam (AIP). 4MOST is currently in its Preliminary Design Phase with an expected start of science operations in 2021. Two third of fibres go to two Low Resolution Spectrographs with three channels per spectrograph. Each low resolution spectrograph is composed of 812 scientific and 10 calibration fibres using 85μm core fibres at f/3, a 200mm beam for an off-axis collimator associated to its Schmidt corrector, 3 arms with f/1.73 cameras and standard 6k x 6k 15μm pixel detectors. CRAL has the responsibility of the Low Resolution Spectrographs. In this paper, the optical design and performances of 4MOST Low Resolution Spectrograph designed for 4MOST PDR in June, 2016 will be presented. Special emphasis will be put on the Low Resolution Spectrograph system budget and performance analysis.
Integration and testing of the DESI spectrograph prototype
Author(s):
S. Perruchot;
A. Secroun;
P.-E. Blanc;
S. Ronayette;
X. Régal;
G. Castagnoli;
A. Le Van Suu;
A. Ealet;
J.-G. Cuby;
A. Elliot;
K. Honscheid;
P. Jelinsky
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation probe. The KPNO Mayall telescope will deliver light to 5000 fibers feeding ten broadband spectrographs. A consortium of Aix-Marseille University (AMU) and CNRS laboratories (LAM, OHP and CPPM) together with the WINLIGHT Systems company (Pertuis-France) has committed to integrate and validate the performance requirements of the full spectrographs, equipped with their cryostats, shutters and other mechanisms. An AIT plan has been defined and dedicated test equipment has been designed and implemented. This equipment simulates the fiber input illumination from the telescope, and offers a variety of continuum and line sources. Flux levels are adjustable and can illuminate one or several fibers along the test slit. It is fully remotely controlled and interfaced to the Instrument Control System. Specific analysis tools have also been developed to verify and monitor the performance and stability of the spectrographs. All these developments are described in details.
ProtoDESI: risk reduction experiment for the Dark Energy Spectroscopic Instrument
Author(s):
Parker Fagrelius;
Charles Baltay;
Christopher Bebek;
Robert Besuner;
Francisco J. Castander;
Arjun Dey;
Elizabeth Buckley-Geer;
Ann Elliott;
William Emmet;
Brenna Flaugher;
Irena Gershkovich;
Klaus Honscheid;
Dick Joyce;
Stephen Kent;
Robert Marshall;
Ronald Probst;
David Rabinowitz;
Kevin Reil;
David Schlegel;
Michael Schubnell;
Santiago Serrano;
Joseph Silber;
David Sprayberry;
Greg Tarle
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq. deg. will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe the ProtoDESI experiment, planned for installation and commissioning at the Mayall telescope in the fall of 2016, which will test the fiber positioning system for DESI. The ProtoDESI focal plate, consisting of 10 fiber positioners, illuminated fiducials, and a guide, focus and alignment (GFA) sensor module, will be installed behind the existing Mosaic prime focus corrector. A Fiber View Camera (FVC) will be mounted to the lower surface of the primary mirror cell and a subset of the Instrument Control System (ICS) will control the ProtoDESI subsystems, communicate with the Telescope Control System (TCS), and collect instrument monitoring data. Short optical fibers from the positioners will be routed to the back of the focal plane where they will be imaged by the Fiber Photometry Camera (FPC) or back-illuminated by a LED system. Target objects will be identified relative to guide stars, and using the GFA in a control loop with the ICS/TCS system, the guide stars will remain stable on pre-identified GFA pixels. The fiber positioners will then be commanded to the target locations and placed on the targets iteratively, using the FVC to centroid on back-illuminated fibers and fiducials to make corrective delta motions. When the positioners are aligned with the targets on-sky, the FPC will measure the intensities from the positioners’ fibers which can then be dithered to look for intensity changes, indicating how well the fibers were initially positioned on target centers. The final goal is to operate ProtoDESI on the Mayall telescope for a 6-hour period during one night, successfully placing targets on the intended fibers for the duration of a typical DESI science exposure.
Integration and characterization of the cryogenic system of MEGARA
Author(s):
D. Ferrusca R.;
M. E. Cisneros G.;
M. Velázquez ;
J. A. Zenteno H.;
A. Gil de Paz;
J. Gallego;
E. Carrasco;
F. C. Sánchez-Moreno;
J. Iglesias-Páramo
Show Abstract
MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical Integral-Field Unit and Multi-Object Spectrograph designed for the GTC (Gran Telescopio de Canarias) 10.4m telescope in La Palma, it is expected that the spectrograph will be delivered to GTC towards the end of 2016. MEGARA includes an open cycle cryostat which harbors the scientific CCD of the instrument at an operating temperature of 153 K, this cryogenic system has been designed and integrated by the “Astronomical Instrumentation Lab for Millimeter Wavelengths” at the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) in Mexico. Early this year the cryostat has finished its fabrication and now it is on AIV phases, in this paper we report the cryostat CCD-head and dewar back integration, vacuum and cryogenic test results are also reported. The final integration of the cryostat with the other components of the instrument is taking place at LICA lab at the Universidad Complutense de Madrid.
Towards the cryogenic sliding mechanism for MOONS-ESO
Author(s):
A. Tozzi;
L. Carbonaro;
T. Oliva;
M. Iuzzolino;
J. Strachan;
P. Rees II
Show Abstract
The Multi-Object Optical and Near-Infrared Spectrograph (MOONS) shall be installed at one of the Very Large Telescopes (VLT) at the European Southern Observatory (ESO) in Paranal Chile. The instrument is being designed and built by an international consortium on behalf of ESO. The design is based on a three arms configuration, RI, YJ and H band, where RI and H have two possible resolutions. To achieve this goal it will be necessary to implement a sliding mechanism changing the dispersers, the filters and the cross dispersion prisms. This article describes the cryogenic exchanger mechanism that is under realization and the preliminary mechanical and optical tests that we have done at the cryogenic facility of Arcetri observatory of Florence. Parts of these test are based on interferometric measurements of the optics to study the behaviour of the mechanical supporting structure, and part are based on the cryogenic sliding system that will be used to move approximately 200 Kg of mass for 350 mm of travel range. The cryogenic sliding system, rails, screws, motors, is based on commercial components as the position measurement device that is based on commercial potentiometers. The results of the tests and performances at cryogenic temperature are reported in this paper.
VIRUS characterization development and results from first batches of delivered units
Author(s):
Briana L. Indahl;
Gary J. Hill;
Niv Drory;
Karl Gebhardt;
Sarah Tuttle;
Jason Ramsey;
Greg Ziemann;
Taylor Chonis;
Trent Peterson;
Andrew Peterson;
Brian L. Vattiat;
Huan Li;
Lei Hao
Show Abstract
The Visible Integral Field Replicable Unit Spectrograph (VIRUS), the instrument for the Hobby Eberly Telescope Dark Energy Experiment (HETDEX), consists of 78 replicable units, each with two integral field spectrographs. Each spectrograph has its own 2kx2k CCD detector with 15 micron pixels. Following alignment, the final stage prior to deployment of each unit is characterization of the 156 spectrograph channels and their CCDs. We describe the laboratory calibration system and scripting that automates this process. Both fiber and continuous (non-spatially modulated) input slits are utilized. Photon transfer curves are made to measure the gain and read noise of each CCD. Pixel flats are also made to correct for pixel-to-pixel QE variations. Relative throughput measurements of each unit are made using the same lab fiber bundle for consistency, and fiber profiles are characterized for later use by the CURE data reduction package. Replicable unit instruments provide a cost effective solution for scaling up instruments for large and extremely large class telescopes. Because VIRUS is the first massively replicated instrument, we have the opportunity to examine the end result of variations in the manufacturing processes that go into production. This paper presents the characterization setup for VIRUS units and compares the performance and variability of processed units with specifications for HETDEX.
Metrology camera system of prime focus spectrograph for Suburu telescope
Author(s):
Shiang-Yu Wang;
Richard C. Y. Chou;
Pin-Jie Huang;
Hung-Hsu Ling;
Jennifer Karr;
Yin-Chang Chang;
Yen-Sang Hu;
Shu-Fu Hsu;
Hsin-Yo Chen;
James E. Gunn Sr.;
Dan J. Reiley;
Naoyuki Tamura;
Naruhisa Takato;
Atsushi Shimono
Show Abstract
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph designed for the prime focus of the 8.2m Subaru telescope. PFS will cover a 1.3 degree diameter field with 2394 fibers to complement the imaging capabilities of Hyper SuprimeCam. To retain high throughput, the final positioning accuracy between the fibers and observing targets of PFS is required to be less than 10 microns. The metrology camera system (MCS) serves as the optical encoder of the fiber motors for the configuring of fibers. MCS provides the fiber positions within a 5 microns error over the 45 cm focal plane. The information from MCS will be fed into the fiber positioner control system for the closed loop control. MCS will be located at the Cassegrain focus of Subaru telescope in order to cover the whole focal plane with one 50M pixel Canon CMOS camera. It is a 380mm Schmidt type telescope which generates a uniform spot size with a ~10 micron FWHM across the field for reasonable sampling of the point spread function. Carbon fiber tubes are used to provide a stable structure over the operating conditions without focus adjustments. The CMOS sensor can be read in 0.8s to reduce the overhead for the fiber configuration. The positions of all fibers can be obtained within 0.5s after the readout of the frame. This enables the overall fiber configuration to be less than 2 minutes. MCS will be installed inside a standard Subaru Cassgrain Box. All components that generate heat are located inside a glycol cooled cabinet to reduce the possible image motion due to heat. The optics and camera for MCS have been delivered and tested. The mechanical parts and supporting structure are ready as of spring 2016. The integration of MCS will start in the summer of 2016. In this report, the performance of the MCS components, the alignment and testing procedure as well as the status of the PFS MCS will be presented.
The current status of prime focus instrument of Subaru prime focus spectrograph
Author(s):
Shiang-Yu Wang;
Mark A. Schwochert;
Pin-Jie Huang;
Hsin-Yo Chen;
Masahiko Kimura;
Richard C. Y. Chou;
Yin-Chang Chang;
Yen-Sang Hu;
Hung-Hsu Ling;
Chaz N. Morantz;
Dan J. Reiley;
Peter Mao;
David F. Braun;
Chih-Yi Wen;
Chi-Hung Yan;
Jennifer Karr;
James E. Gunn Sr.;
Graham Murray;
Naoyuki Tamura;
Naruhisa Takato;
Atsushi Shimono;
Decio Ferreira;
Leandro Henrique dos Santos;
Ligia Souza Oliveira;
Antonio Cesar de Oliveira;
Lucas Souza Marrara
Show Abstract
The Prime Focus Spectrograph (PFS) is a new optical/near-infrared multi-fiber spectrograph design for the prime focus of the 8.2m Subaru telescope. PFS will cover 1.3 degree diameter field with 2394 fibers to complement the imaging capability of Hyper SuprimeCam (HSC). The prime focus unit of PFS called Prime Focus Instrument (PFI) provides the interface with the top structure of Subaru telescope and also accommodates the optical bench in which Cobra fiber positioners are located. In addition, the acquisition and guiding cameras (AGCs), the optical fiber positioner system, the cable wrapper, the fiducial fibers, illuminator, and viewer, the field element, and the telemetry system are located inside the PFI. The mechanical structure of the PFI was designed with special care such that its deflections sufficiently match those of the HSC’s Wide Field Corrector (WFC) so the fibers will stay on targets over the course of the observations within the required accuracy. In this report, the latest status of PFI development will be given including the performance of PFI components, the setup and performance of the integration and testing equipment.
iSHELL: a construction, assembly and testing
Author(s):
John Rayner;
Alan Tokunaga;
Dan Jaffe;
Morgan Bonnet;
Greg Ching;
Mike Connelley;
Dan Kokubun;
Charles Lockhart;
Eric Warmbier
Show Abstract
iSHELL is 1.10-5.3 μm high spectral resolution spectrograph being built for the NASA Infrared Telescope Facility on Maunakea, Hawaii. Dispersion is accomplished with a silicon immersion grating in order to keep the instrument small enough to be mounted at the Cassegrain focus of the telescope. The white pupil spectrograph produces resolving powers of up to R=75,000. Cross-dispersing gratings mounted in a tilt-able mechanism allow observers to select different wavelength ranges and, in combination with a slit wheel and Dekker mechanism, slit lengths ranging from 5ʺ″ to 25ʺ″. One Teledyne 2048x2048 Hawaii 2RG array is used in the spectrograph, and one Raytheon 512x512 Aladdin 2 array is used in a slit viewer for object acquisition and guiding. First light is expected in mid-2016. In this paper we discuss details of the construction, assembly and laboratory testing.
Performance of MEGARA spectrograph optical elements
Author(s):
E. Carrasco;
G. Páez;
R. Izazaga;
J. de la Luz Hurtado;
C. Pérez;
F. Granados;
D. Aguirre;
E. Percino;
J. Reyes;
A. Gil de Paz;
J. Gallego;
J. Iglesias
Show Abstract
MEGARA is the new IFU and multiobject spectrograph for Gran Telescopio Canarias. The spectograph will offer spectral resolution Rfwhm~ 6,000, 12,000 and 18,700. Except for the optical fibers and microlenses, the complete MEGARA optical system has been manufactured in Mexico. This includes a field lens, a 5-lenses collimator, a 7-lenses camera and a complete set of volume phase holographic gratings with 36 flat windows and 24 prisms. All these elements are very large and complex, with very efficient antireflection coatings. Here the optical performance of MEGARA collimator and camera lenses and the field lens is presented.
Design and testing of AR coatings for MEGARA optics
Author(s):
R. Ortiz;
E. Carrasco;
G. Páez;
O. Pompa;
E. Sanchez-Blanco;
A. Gil de Paz;
J. Gallego;
J. Iglesias-Páramo
Show Abstract
We present the antireflection coatings of the optical elements of MEGARA, the new integral field and multi-object spectrograph for the Gran Telescopio Canarias. We describe the methodology for optimizing the solutions. We also present the results of the final deposited coatings. The main optics require broadband coatings in the range from 370 nm to 980 nm for different materials with a mean R<1.3% at specific angles of incidence in each surface. For each material a specific arrangement of thicknesses of the same eight layers were produced and tested. For the spectrograph pupil elements four layer coatings were designed and produced R<0.3%. The design of main optics and pupil elements coatings have been shared between INAOE and CIO. The coating depositions have been performed at CIO in the Integrity 39 Denton Vacuum Deposition System. The main optics final coatings fulfill MEGARA requirements.
Optical design for the TAIPAN and HECTOR transmissive spectrographs
Author(s):
Robert Content;
Jon Lawrence;
Luke Gers;
Ross Zhelem
Show Abstract
TAIPAN is a multi-fibre project for the UK-Schmidt Telescope and Hector is a multi-IFU project for the Anglo- Australian Telescope (AAT) using fibres. Many different transparent designs were studied covering a large parameter space. An important trade-off study was between the use of microlenses on the slit or just bare fibres. Microlenses have disadvantages but permit considerable simplification of the collimator by making the beam very slow. The disadvantages are more important with the UK-Schmidt due to the faster beam from the telescope. With microlenses, the collimator can be a unique spherical plano-convex lens significantly smaller than the mirror that would be needed in a reflective design. For Hector, 26 different camera designs where done to cover the parameter space for 2k x 2k, 2k x 4k, or 4k x 4k detectors, and for 50, 75 or 100 micron fibre cores, with or without microlenses, with a triplet in the camera or a doublet plus singlet, and with a maximum wavelength of 1 or 1.05 microns. Not all combinations were designed but for each parameter there are at least two representative cameras with all other parameters identical. A preliminary cost estimate was made for the most promising designs which permitted to reduce them to 3 for more detailed designing. Also, a theoretical study was done of the PSF obtained with highly packed microlenses at the slit with no space between them and imaging to 2 pixels per microlenses. This maximizes the number of fibres per spectrograph, and thus the total field of view of all IFUs together, but it comes with some disadvantages.
Wide-field corrector for 4MOST: design details and MAIV processes
Author(s):
Nicolas Azais;
Samuel C. Barden;
Greg Smith;
Damien Jones;
Bernard Delabre;
Sylvain Egron
Show Abstract
The 4-meter Multi-Object Spectroscopic Telescope (4MOST) is a wide-field, high-multiplex spectroscopic survey facility under development for the Visible and Infrared Survey Telescope for Astronomy (VISTA) of the European Southern Observatory (ESO). The primary and secondary mirrors (M1 and M2) together with the Wide Field Corrector (WFC) system provide a pupil-centric and aberration corrected focal surface. The WFC is also an integral part of the metrology system. At the focal surface, we meet two wave front sensing (WFS) systems, a deployable camera at commissioning, an acquisition and guiding (A and G) unit and a secondary guiding unit. This paper provides an overview of design details and Manufacture, Assembly, Integration and Verification (MAIV) processes for the 4MOST WFC system.
DESI-GFA testbench facilities for CCDs characterization
Author(s):
Jorge Jiménez ;
José M. Illa;
Juan de Vicente;
Ricard Casas
Show Abstract
The DESI-GFA subsystem, used for Guiding, Focusing and Alignment, is one of the key parts for the DESI instrument (The Dark Energy Spectroscopic Instrument), planned for the Mayall 4-meter telescope at Kitt Peak National Observatory, Arizona, U.S. On this paper are presented the test bench facilities developed for the characterization of an e2v CCD230-42 CCD which is expected to be used at room temperature on each one of the ten small cameras composing the DESI-GFA system.
The alignment and assembly of the DESI prime focus corrector
Author(s):
David Brooks;
Peter Doel;
Robert Besuner;
Brenna Flaugher;
Giuseppe Gallo;
Gaston Gutierrez;
Stephen Kent;
Michael Lampton;
Michael Levi;
Ming Liang;
Timothy N. Miller;
David Sprayberry;
Andrew Stefanik
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI), which is currently under construction, is designed to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fibre optic positioners. The fibres in turn feed ten broad-band spectrographs. The prime focus corrector for DESI consists of six lenses that range in diameter from 0.80 - 1.14 meters and from 83 - 237 kg in weight. The alignment of the large lenses of the optical corrector poses a significant challenge as in order to meet the fibre throughput requirements they have to be aligned to within a tolerance of ~50 micrometres. This paper details the design for the cells that will hold the lenses and the alignment and assembly procedure for the mounting of the lenses into the cells and into the complete barrel assembly. This is based on the experience obtained from the alignment of the Dark Energy Camera (DECam) instrument which was successfully assembled and aligned by the same team and we include in the paper the lessons learnt and design modifications that will be implemented on the DESI system.
The prime focus corrector for dark energy spectroscopic instrument
Author(s):
Peter Doel;
Robert Besuner;
David Brooks;
Brenna Flaugher;
Giuseppe Gallo;
Gaston Gutierrez;
Stephen Kent;
Michael Lampton;
Michael Levi;
Ming Liang;
Timothy Miller;
David Sprayberry
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI), currently under construction, is designed to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. This paper describes the overall design and construction status of the prime focus corrector. The size and complexity of the system poses significant design and production challenges. The optics of the corrector consists of six lenses, ranging from 0.8 - 1.14m in diameter, two of which can be rotated to act as an atmospheric dispersion corrector. These lenses are mounted in custom cells that themselves are mounted in a barrel assembly the alignment of which can be actively controlled by a hexapod system to micrometer precision. The whole assembly will be mounted at the prime focus of the Mayall 4m telescope at Kitt Peak observatory and will be one of the largest lens systems ever built for an optical telescope. Construction of the corrector began in 2014 and is well advanced. The system is due to be delivered to the telescope for installation in early 2018.
Implementation and performance of the metrology system for the multi-object optical and near-infrared spectrograph MOONS
Author(s):
Holger Drass;
Leonardo Vanzi;
Miguel Torres-Torriti;
Rolando Dünner ;
Tzu-Chiang Shen;
Francisco Belmar;
Lousie Dauvin;
Tomás Staig;
Jonathan Antognini;
Mauricio Flores;
Yerko Luco;
Clémentine Béchet;
David Boettger;
Steven Beard;
David Montgomery;
Stephen Watson;
Alexandre Cabral;
Mahmoud Hayati;
Manuel Abreu;
Phil Rees II;
Michele Cirasuolo;
William Taylor;
Alasdair Fairley
Show Abstract
The Multi-Object Optical and Near-infrared Spectrograph (MOONS) will cover the Very Large Telescope's (VLT) field of view with 1000 fibres. The fibres will be mounted on fibre positioning units (FPU) implemented as two-DOF robot arms to ensure a homogeneous coverage of the 500 square arcmin field of view. To accurately and fast determine the position of the 1000 fibres a metrology system has been designed. This paper presents the hardware and software design and performance of the metrology system. The metrology system is based on the analysis of images taken by a circular array of 12 cameras located close to the VLTs derotator ring around the Nasmyth focus. The system includes 24 individually adjustable lamps. The fibre positions are measured through dedicated metrology targets mounted on top of the FPUs and fiducial markers connected to the FPU support plate which are imaged at the same time. A flexible pipeline based on VLT standards is used to process the images. The position accuracy was determined to ~5 μm in the central region of the images. Including the outer regions the overall positioning accuracy is ~25 μm. The MOONS metrology system is fully set up with a working prototype. The results in parts of the images are already excellent. By using upcoming hardware and improving the calibration it is expected to fulfil the accuracy requirement over the complete field of view for all metrology cameras.
4MOST fiber feed preliminary design: prototype testing and performance
Author(s):
Dionne M. Haynes;
Andreas Kelz;
Samuel C. Barden;
Svend-Marian Bauer;
Katjana Ehrlich;
Roger Haynes;
Thomas Jahn;
Allar Saviauk;
Roelof S. de Jong
Show Abstract
The 4MOST instrument is a multi-object-spectrograph for the ESO-VISTA telescope. The 4MOST fiber feed subsystem is composed of a fiber positioner (AESOP) holding 2436 science fibers based on the Echidna tilting spine concept, and the fiber cable, which feeds two low-resolution spectrographs (1624 fibers) and one high-resolution spectrograph (812 fibers). In order to optimize the fiber feed subsystem design and provide essential information required for the spectrograph design, prototyping and testing has been undertaken. In this paper we give an overview of the current fiber feed subsystem design and present the preliminary FRD, scrambling, throughput and system performance impact results for: maximum and minimum spine tilt, fiber connectors, cable de-rotator simulator for fiber cable lifetime tests.
Progress on the fabrication of the DESI corrector optics
Author(s):
Timothy N. Miller;
Peter Doel;
David Brooks;
Michael J. Sholl;
Michael E. Levi
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the Kitt Peak National Observatory Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe the status of the DESI corrector optics, a series of 0.8 to 1.1-meter fused silica and borosilicate lenses currently being fabricated to demanding requirements. We will describe the specs for lenses that are finished or underway, including surface figure, homogeneity, and other parameters; the current schedule for lens production; and a comparison against DESI corrector requirements.
Stray light assessment and mitigation for the DESI front-end optical system
Author(s):
Timothy N. Miller;
Michael Lampton;
Robert W. Besuner;
Michael J. Sholl;
Ming Liang;
Scott Ellis
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe, using the Baryon Acoustic Oscillation technique and the growth of structure using redshift-space distortions (RSD). The spectra of 40 million galaxies over 14000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe modeling and mitigation of stray light within the front end of DESI, consisting of the Mayall telescope and the corrector assembly. This includes the creation of a stray light model, quantitative analysis of the unwanted light at the corrector focal surface, identification of the main scattering sources, and a description of mitigation strategies to remove the sources.
PSF modeling by spikes simulations and wings measurements for the MOONS multi fiber spectrograph
Author(s):
G. Li Causi;
D. Lee;
F. Vitali;
F. Royer;
E. Oliva
Show Abstract
The optical design of MOONS, the next generation thousand-fiber NIR spectrograph for the VLT, involves both on-axis reflective collimators and on-axis very fast reflective cameras, which yields both beam obstruction, due to fiber slit and detector support, and image spread, due to propagation within detector substrate. The need to model and control i) the effect of the diffraction spikes produced by these obstructions, ii) the detector-induced shape variation of the Point Spread Function (PSF), and iii) the intensity profile of the PSF wings, leads us to perform both simulations and lab measurements, in order to optimize the spider design and built a reliable PSF model, useful for simulate realistic raw images for testing the data reduction. Starting from the unobstructed PSF variation, as computed with the ZEMAX software, we numerically computed the diffraction spikes for different spider shapes, to which we added the PSF wing profile, as measured on a sample of the MOONS VPH diffraction grating. Finally, we implemented the PSF defocusing due to the thick detector (for the visible channel), we convolved the PSF with the fiber core image, and we added the optical ghosts, so finally obtaining a detailed and realistic PSF model, that we use for spectral extraction testing, cross talk estimation, and sensitivity predictions.
DESI focal plate mechanical integration and cooling
Author(s):
A. R. Lambert;
R. W. Besuner;
T. M. Claybaugh;
J. H. Silber
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique[1]. The spectra of 40 million galaxies over 14000 sq. deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. This paper describes the mechanical integration of the DESI focal plate and the thermal system design. The DESI focal plate is comprised of ten identical petal assemblies. Each petal contains 500 robotic fiber positioners. Each petal is a complete, self-contained unit, independent from the others, with integrated power supply, controllers, fiber routing, and cooling services. The major advantages of this scheme are: (1) supports installation and removal of complete petal assemblies in-situ, without disturbing the others, (2) component production, assembly stations, and test procedures are repeated and parallelizable, (3) a complete, full-scale prototype can be built and tested at an early date, (4) each production petal can be surveyed and tested as a complete unit, prior to integration, from the fiber tip at the focal surface to the fiber slit at the spectrograph. The ten petal assemblies will be installed in a single integration ring, which is mounted to the DESI corrector. The aluminum integration ring attaches to the steel corrector barrel via a flexured steel adapter, isolating the focal plate from differential thermal expansions. The plate scale will be kept stable by conductive cooling of the petal assembly. The guider and wavefront sensors (one per petal) will be convectively cooled by forced flow of air. Heat will be removed from the system at ten liquid-cooled cold plates, one per petal, operating at ambient temperature. The entire focal plate structure is enclosed in an insulating shroud, which serves as a thermal barrier between the heat-generating focal plate components and the ambient air of the Mayall dome, to protect the seeing[2].
Design of the calibration unit for the WEAVE multi-object spectrograph at the WHT
Author(s):
Lilian Domínquez;
Diego Cano;
Neil O'Mahony;
Carlos Martín;
Sergio Picó ;
Chris Benn;
Scott Trager;
Émilie Lhomé;
Andy Ridings;
Cecilia Fariña;
D. C. Abrams;
Marc Balcells;
Mike Irwin;
Jim Lewis;
Gavin Dalton;
J. A. Aguerri;
P. Bonifacio;
A. Vallenari;
E. Carrasco
Show Abstract
WEAVE is the next-generation spectroscopic facility for the William Herschel Telescope (WHT), offering multi-object (1000 fibres) and integral-field spectroscopy at two resolutions (R ~ 5000, 20000) over a 2-deg field of view at prime focus. WEAVE will (mainly) provide optical follow up of ground-based (LOFAR) and space-based (GAIA) surveys. First light is expected in mid 2018. Here, we describe the calibration unit, which will be adapted from an existing unit for the AF2+WYFFOS spectrograph (WEAVE's precursor) at the WHT. We summarise the results from a thorough characterisation of current performance (e.g. intensity, stability and focal-plane coverage of illumination as a function of lamp type and wavelength). We then set out our plans for upgrading the unit and its control systems to meet the WEAVE science and operational requirements. We conclude from this assessment that the upgraded AF2+WYFFOS calibration unit will meet the requirements for WEAVE. The design of the WEAVE calibration unit is now complete.
SUBARU prime focus spectrograph: integration, testing and performance for the first spectrograph
Author(s):
F. Madec;
A. Le Fur;
D. Le Mignant;
K. Dohlen;
R. Barrette;
M. Belhadi;
S. Pascal;
S. Smee;
J. Gunn;
J. Le Merrer;
M. Lorred;
M. Jaquet;
P. Balard;
P. Blanchard;
W. Tao;
V. Lapere;
J. F. Gabriel;
C. Loomis;
M. Golebiowski;
M. Hart;
L. Oliveira;
A. Oliveira;
N. Tamura;
A. Shimono
Show Abstract
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project for Subaru telescope consists in four identical spectrographs fed by 600 fibers each. Each spectrograph is composed by an optical entrance unit that creates a collimated beam and distributes the light to three channels, two visibles and one near infrared. This paper presents the on-going effort for the tests and integration process for the first spectrograph channel: we have developed a detailed Assembly Integration and Test (AIT) plan, as well as the methods, detailed processes and I and T tools. We describe the tools we designed to assemble the parts and to test the performance of the spectrograph. We also report on the thermal acceptance tests we performed on the first visible camera unit. We also report on and discuss the technical difficulties that did appear during this integration phase. Finally, we detail the important logistic process that is require to transport the components from other country to Marseille.
SAMOS: a versatile multi-object-spectrograph for the GLAO system SAM at SOAR
Author(s):
Massimo Robberto;
Megan Donahue;
Zoran Ninkov;
Stephen A. Smee;
Robert H. Barkhouser;
Mario Gennaro;
Andrei Tokovinin
Show Abstract
The 4.1-m SOAR telescope can play a unique role for LSST follow-up studies through an efficient use of its laser-guided Adaptive Optics Module (SAM) that routinely delivers images with FWHM <0.5” over a uniquely large 3’x3’ field of view. To exploit this platform we have conceived SAMOS, a MEMS-based slit spectrograph capable of acquiring in a few seconds single or multiple targets with extreme precision. SAMOS can capture R ~ 2,000 – 2, 500 spectra with a nominal 0:33" slit width in the 3,500-9,500 Å spectral range reaching in 3600 s median SNR=5 at AB=22.9 with the red grating and 23.5 with the blue grating, comparable to 8-m class telescopes working in seeing limited conditions. In this contribution we present the SAMOS opto-mechanical design, concept of operation and provide a few examples of compelling science programs that can uniquely benefit from SAMOS sensitivity, angular resolution, versatility and simplicity of use.
EMIR electronics AIV and commisioning
Author(s):
Miguel Núñez ;
Enrique Joven ;
Patricia Fernandez ;
Francisco Garzón ;
Carmen M. Barreto;
Jesús Patrón ;
Ángel Mato;
Heidy Moreno;
Oscar Tubio ;
Nauzet Vega
Show Abstract
EMIR is the NIR imager and multi-object spectrograph common user instrument for the GTC and it has recently passed its first light on sky. EMIR was built by a Consortium of Spanish and French institutes led by the IAC. EMIR has finished its AIV phase at IAC facilities and it is now in commissioning on sky at GTC telescope, having completed the first run. During previous cool downs the EMIR subsystems have been integrated in the instrument progressively for verifying its functionality and performance. In order to fulfil the requirements, prepare the instrument to be in the best conditions for installation in the telescope and to solve unexpected electronics drawbacks, some changes in the implementation have been accomplished during AIV. In this paper it is described the adjustments, modifications and lessons learned related to electronics along AIV stages and the commissioning in the GTC. This includes actions in different subsystems: Hawaii2 detector and its controller electronics, Detector translation Unit, Multi object slit, wheels for filters and grisms, automatisms, vacuum, cryogenics and general electronics.
4MOST: the high-resolution spectrograph
Author(s):
W. Seifert;
W. Xu;
P. Buschkamp;
C. Feiz;
A. Saviauk;
S. Barden;
A. Quirrenbach;
H. Mandel
Show Abstract
4MOST (4-meter Multi-Object Spectroscopic Telescope) is a wide-field, fiber-feed, high-multiplex spectroscopic survey facility to be installed on the 4-meter ESO telescope VISTA in Chile. It consists of two identical low resolution spectrographs and one high resolution spectrograph. The instrument is presently in the preliminary design phase and expected to get operational end of 2022. The high resolution spectrograph will afford simultaneous observations of up to 812 targets - over a hexagonal field of view of ~ 4.1 sq.degrees on sky - with a spectral resolution R>18,000 covering a wavelength range from 393 to 679nm in three channels. In this paper we present the optical and mechanical design of the high resolution spectrograph (HRS) as prepared for the review at ESO, Garching. The expected performance including the highly multiplexed fiber slit concept is simulated and its impact on the optical performance given. We show the thermal and finite element analyses and the resulting stability of the spectrograph under operational conditions.
4MOST metrology system image processing
Author(s):
Roland Winkler;
Samuel C. Barden;
Allar Saviauk
Show Abstract
The 4-meter Multi-Object Spectroscopic Telescope (4MOST) instrument uses ~ 2400 individually positioned optical fibres to couple the light of targets into its spectrographs. The metrology system determines the position of the back-illuminated fibres on the focal surface of the telescope. It consists of 4 identical cameras that are mounted on the spider vanes of the secondary mirror of the VISTA telescope and look through the entire optical train, including M1, M2 and the WFC/ADC unit. Here, we describe the image and data processing steps of the metrology system as well as present results from our 1 in 10 sized lab prototype.
The DESI fiber positioner system
Author(s):
Michael Schubnell;
Jon Ameel;
Robert W. Besuner;
Irena Gershkovich;
Philipp Hoerler;
Jean-Paul Kneib;
Henry D. Heetderks;
Joseph H. Silber;
Gregory Tarlé;
Curtis Weaverdyck
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the baryon acoustic oscillation technique. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5,000 fiber optic positioners feeding ten broad-band spectrographs. The positioners have eccentric axis kinematics. Actuation is provided by two 4mm diameter DC brushless gear-motors. An attached electronics board accepts a DC voltage for power and CAN messages for communications and drives the two motors. The positioner accepts the ferrulized and polished fiber and provides a mechanically safe path through its internal mechanism. Positioning is rapid and accurate with typical RMS errors of less than 5 μm.
Detector and control system design and performance for the SuMIRe prime focus spectrograph (PFS) cameras
Author(s):
James E. Gunn Sr.;
Roger Fitzgerald;
Murdock Hart;
Stephen C. Hope;
Craig Loomis;
Grant O. Peacock;
Mirek Golebiowski;
Michael A. Carr;
Stephen A. Smee;
Naoyuki Tamura;
Naruhisa Takato;
Atsushi Shimono
Show Abstract
We discuss the design, construction, and performance of the detector system for the SuMIRe Prime Focus Spectrograph (PFS). SuMIRe PFS is a massively multi-plexed ground-based spectrograph consisting of four identical spectrograph modules, each receiving roughly 600 fibers from a 2394 fiber robotic positioner at the prime focus. Each spectrograph module has three channels covering the wavelength ranges 3800Å-6400Å, 6400-9550Å. and 9550-12600Å, with the dispersed light being imaged in each channel by a f/1.07 vacuum Schmidt camera. In this paper we describe the CCD system for the two visible channels and the overall control and data acquisition systems for the cameras, and discuss the test system for detector characterization. This system will also serve for testing the H4RG infrared detectors for the near IR channel. The first red system, utilizing a 200-micron thick fully depleted p-channel Hamamatsu CCD, is finished and has been tested. The performance is excellent, with low noise, high CTE, and very good low-level and overall linearity. The test system uses essentially all the `flight' electronics and power supplies, in an effort to assess performance in an environment as nearly like the one to be seen in operation as possible.
Development of the fibre positioning unit of MOONS
Author(s):
David Montgomery;
David Atkinson;
Stephen Beard;
William Cochrane;
Holger Drass;
Isabelle Guinouard;
David Lee;
William Taylor;
Phil Rees;
Steve Watson
Show Abstract
The Multi-Object Optical and Near-Infrared Spectrograph (MOONS) will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.64μm-1.8μm, with a multiplex capability of over 1000 fibres. This can be configured to produce spectra for chosen targets and have close proximity sky subtraction if required. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode. The fibre positioning units are used to position each fibre independently in order to pick off each sub field of 1.0” within a circular patrol area of ~85” on sky (50mm physical diameter). The nominal physical separation between FPUs is 25mm allowing a 100% overlap in coverage between adjacent units. The design of the fibre positioning units allows parallel and rapid reconfiguration between observations. The kinematic geometry is such that pupil alignment is maintained over the patrol area. This paper presents the design of the Fibre Positioning Units at the preliminary design review and the results of verification testing of the advanced prototypes.
Very fast transmissive spectrograph designs for highly multiplexed fiber spectroscopy
Author(s):
Will Saunders
Show Abstract
Very fast (f/1.2 and f/1.35) transmissive spectrograph designs are presented for Hector and MSE. The designs have 61mm x 61mm detectors, 4 or 5 camera lenses of aperture less than 228mm, with just 6 air/glass surfaces, and rely on extreme aspheres for their imaging performance. The throughput is excellent, because of the i-line glasses used, the small number of air/glass surfaces.
Fiber system design for the Dark Energy Spectroscopic Instrument (DESI)
Author(s):
Claire Poppett;
Ray Sharples;
Jerry Edelstein;
Jürgen Schmoll;
David Bramall;
Parker Fagrelius
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe the Fiber Systems design with specific emphasis on novel approaches and essential elements that lead to exceptional performance.
Optical fiber termination method for the Dark Energy Spectroscopic Instrument (DESI)
Author(s):
Claire Poppett;
Jerry Edelstein;
Yuzo Ishikawa;
Zakios Meghrouni-Brown;
Parker Fagrelius
Show Abstract
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe the method we use to optically terminate the fibers which offers many advantages over methods that have been used in the past.
The Maunakea Spectroscopic Explorer: throughput optimization
Author(s):
Nicolas Flagey;
Shan Mignot;
Kei Szeto;
Alan McConnachie;
Rick Murowinski
Show Abstract
The Maunakea Spectroscopic Explorer (MSE) will obtain millions of optical to near-infrared spectra, at low (R~2,500) to high (R~40,000) spectral resolution, via a highly multiplexed (~3000) fiber-fed system. Key science programs for MSE (black hole reverberation mapping, stellar population analysis at high redshift, subkm/ s velocity accuracy for stellar astrophysics) will target faint Galactic and extra-galactic targets (typical visual magnitudes up to 24). MSE will thus need to achieve the highest throughput possible over the 360 to 1800 nm wavelength range. Here we discuss building an optimized throughput budget in terms of performance allocation and technical solutions to steer the concept design studies.
Operational challenges for astronomical instrumentation in Antarctica: results from five years of environmental monitoring of AMICA at Dome C
Author(s):
Mauro Dolci;
Angelo Valentini;
Daniele Tavagnacco;
Amico Di Cianno;
Oscar Straniero
Show Abstract
The Antarctic Plateau is one of the best observing sites on Earth, especially for infrared astronomy. The extremely low temperatures (down to -80°C), the low pressure (around 650 mbar) and the very dry atmosphere (PWV less than 1 mm) allow for a very clear and dark sky, as well as for a very low instrumental background. These unique properties, however, make it also very difficult to install and operate astronomical instrumentation. AMICA (Antarctic Multiband Infrared CAmera) is an instrument especially designed for Antarctic operation, whose installation at Dome C has been completed in 2013. Since then it has been continuously working over the last five years, monitoring and controlling in particular the environmental and operating conditions through a dedicated application, its Environmental Control System (ECS). The recorded behavior of AMICA highlighted a set of peculiar aspects of the site that are hard to consider a priori. Although mechanical and electronic COTS components can reliably work in thermally insulated and controlled boxes, simple insulation causes their overheating because of the air dryness and rarefaction which make the heat transfer extremely inefficient. Heat removal is also a real problem when managing heavy-duty devices like cryocoolers, whose excess power removal needs to be fast and efficient. Finally, the lack of an electrical ground generates a wide variety of transient electrical and electromagnetic phenomena which often make electronic instrumentation very unstable. A list of new recommendations is therefore presented, as a guideline for future astronomical instruments operating in Antarctica.
Study of the impact of E-ELT and MICADO distortion and wavefront errors residuals on the MICADO astrometric observations
Author(s):
Gabriele Rodeghiero;
Jörg-Uwe Pott;
Peter Bizenberger
Show Abstract
The paper describes the developments towards an end-to-end optical model based on a commercial ray tracing software for studying the effects of the telescope and instrumental instabilities on the Multi-AO Imaging Camera for Deep Observations (MICADO). The primary goal and observing mode of MICADO is imaging, with a focus on relative astrometry with an accuracy of about 50 μas. To achieve this ambitious goal a careful examination of the possible random and systematic effects that can influence the astrometric accuracy is required. Here we concentrate on the perturbations coming from the different telescope and instrumental instabilities, mainly related to the static and dynamical perturbations of the European-Extremely Large Telescope (E-ELT) optics, the cold optics tolerances of the instrument and the intrinsic geometric distortions of both the systems. ESO developed an extended dataset of the E-ELT perturbations that are integrated inside the optical model of the telescope and the instrument relay optics for gathering the aberrated wavefronts. The wavefront error residuals are then propagated inside the system to check the distortions and their effects on the astrometric measurement at the instrument focal plane. From our analysis the dominating instrumental errors are: (i) the telescope induced distortions, in the order of => 100μas, that originate from the optics misalignments and presumably vary over <= 1hr time-scales, and must be calibrated against sky measurements; (ii) the instrument optics induced distortions that can reach ∼ 1 arcsec levels, but are more stable than the telescope perturbations. They will be calibrated with the use of an astrometric calibration mask. We derived the order of magnitude of the astrometric distortions of E-ELT and MICADO. The results of our study will help to define an efficient instrumental calibration strategy against the astrometric error of the instrument.
GMTIFS: challenging optical design problems and their solutions for the GMT integral-field spectrograph
Author(s):
John Hart;
Gabe Bloxham;
Robert Boz;
Brady Espeland;
Robert Sharp
Show Abstract
GMTIFS is a first generation instrument for the Giant Magellan Telescope (GMT). It is a combined Imager and Integral Field Spectrograph (IFS) designed to work with the Adaptive Optics (AO) Systems of the GMT. Working at the diffraction limit of the GMT and satisfying the challenging AO interface requirements and constraints results in unique optical challenges. We describe two of these challenges and how we have addressed them. The GMT has a direct feed architecture that maximizes transmission and reduces emissivity. This means that the cryostat window is tilted to reflect visual wavelengths to the external Visual Wave Front Subsystem (VWS). For a plane-parallel window, this tilt causes astigmatism in the transmitted beam that must be corrected. A corrective system using two plates, tilted and slightly wedged in opposite directions, is used. Geometry and performance of the system is described. Another challenging problem is the optical design of the anamorphic field projector. The Integral Field Unit of GMTIFS requires that a small field delivered to it be projected onto an Image Slicer at much larger scale, with the magnification in the spectral direction being twice that in the spatial direction so that the spaxels are square when referred to the sky. Output images must be coincident in the spectral and spatial projections in both the field and pupil domains. Additionally, field and pupil image locations must be independently controllable so that they can be made coincident for interchangeable units that provide a range of output field scales. A two-mirror system that satisfies these requirements is described.
MICADO: the camera support structure at the E-ELT Nasmyth focus
Author(s):
Harald E. Nicklas;
Heiko Anwand-Heerwart;
Josef Schubert;
Petra Rhode
Show Abstract
MICADO is one of the first light instruments at the E-ELT and is designed to work with the MCAO system MAORY. The ability to operate in a stand-alone mode without MAORY includes an additional SCAO wavefront sensing system. Therefore, the instrument support structure has to fulfil two purposes, a) the positioning of the camera in its stand-alone mode and b) when it will be mounted downstream of the MCAO facility MAORY. The instrument support structure of MICADO is addressed regarding its basic functionalities such as passive and possible active positioning of the instrument. Very first FEA results will be given as well as other performance assessments.
Design of a large image derotator for the E-ELT instrument MICADO
Author(s):
Santiago Barboza;
Jörg-Uwe Pott;
Ralf-Rainer Rohloff;
Friedrich Müller;
Jörg Wagner;
Hans J. Kärcher
Show Abstract
The Multi-AO Imaging Camera for Deep Observations (MICADO), a first light instrument for the 39 m European Extremely Large Telescope (E-ELT), is being designed and optimized to work with the Multi-Conjugate Adaptive Optics (MCAO) module MAORY (0.8-2.5 μm). The current concept of the MICADO instrument consists of a structural cryostat (2.1 m diameter and 2 m height) with the wavefront sensor (WFS) on top. The cryostat is mounted via its central flange with a direct interface to a large 2.5-m-diameter high-precision bearing, which rotates the entire camera (plus wavefront sensor) assembly to allow for image derotation without individually moving optical elements. The whole assembly is suspended at 3.6 m above the E-ELT Nasmyth platform by a Hexapod-type support structure. We describe the design of the MICADO derotator, a key mechanism that must precisely rotate the cryostat/SCAO-WFS assembly around its optical axis with an angular positioning accuracy better than 10 arcsec, in order to compensate the field rotation due to the alt-azimuth mount of the E-ELT. Special attention is being given to simulate the performance of the derotator during the design phase, in which both static and dynamics behaviors are being considered in parallel. The statics flexure analysis is done using a detailed Finite Element Model (FEM), while the dynamics simulation is being developed with the mathematical model of the derotator implemented in Matlab/Simulink. Finally, both aspects must be combined through a realistic end-to-end model. The experiment designed to prove the current concept of the MICADO derotator is also presented in this work.
A new test facility for the E-ELT infrared detector program
Author(s):
Jean Louis Lizon;
Paola Amico;
Martin Brinkmann;
Bernard Delabre;
Gert Finger;
Ivan Maria Guidolin;
Ronald Guzman;
Renate Hinterschuster;
Derek Ives;
Barbara Klein;
Marco Quattri
Show Abstract
During the development of the VLT instrumentation program, ESO acquired considerable expertise in the area of infrared detectors, their testing and optimizing their performance. This can mainly be attributed to a very competent team and most importantly to the availability of a very well suited test facility, namely, IRATEC. This test facility was designed more than 15 years ago, specifically for 1K × 1K detectors such as the Aladdin device, with a maximum field of only 30 mm square. Unfortunately, this facility is no longer suited for the testing of the new larger format detectors that are going to be used to equip the future E-ELT instruments. It is projected that over the next 20 years, there will be of the order of 50-100 very large format detectors to be procured and tested for use with E-ELT first and second generation instruments and VLT third generation instruments. For this reason ESO has initiated the in-house design and construction of a dedicated new IR detector arrays test facility: the Facility for Infrared Array Testing (FIAT). It will be possible to mount up to four 60 mm square detectors in the facility, as well as mosaics of smaller detectors. It is being designed to have a very low thermal background such that detectors with 5.3 μm cut-off material can routinely be tested. The paper introduces the most important use cases for which FIAT is designed: they range from performing routine performance measurements on acquired devices, optimization setups for custom applications (like spot scan intra-pixel response, persistence and surface reflectivity measurements), test of new complex operation modes (e.g. high speed subwindowing mode for low order sensing, flexure control, etc.) and the development of new tests and calibration procedures to support the scientific requirements of the E-ELT and to allow troubleshooting the unexpected challenges that arise when a new detector system is brought online. The facility is also being designed to minimize the downtime required to change to a new detector and then cool it down, ready for testing. The status of the opto-mechanical and cryogenic design is also described in detail, with particular emphasis on the technical solutions identified to fulfill the FIAT top level requirements. We will also describe how the FIAT project has been set-up as a training facility for the younger generation of engineers who are expected to take over the job from the experienced engineers and ensure that the lessons learnt in so many years of successful IR instrumentation projects at ESO are captured for this next generation.
HIRES the high-resolution spectrograph for the E-ELT: dynamics and control of the repositioning mechanism for the E-ELT HIRES polarimeter
Author(s):
I. Di Varano;
K. G. Strassmeier;
M. Woche
Show Abstract
A full Stokes dual channel polarimeter for the E-ELT HIRES spectrograph has been envisioned for the intermediate focus f/4.4, operating within a spectral range of 0.4-1.6 μ. It will feed the EELT- HIRES instrument located on the Nasmyth platform via two pairs of dedicated fibers: one fibre pair optimized for the BVRI, the other one optimized for the JH band or any other feasible combination. The instrument must be retractable within a workspace in fulfillment with the ESO requirements on the allocated volume and the dynamic response of the AO tower. For such purpose a swinging arm has been designed with a rotation provided by 5 revolute joints and a jackscrew. Moreover repeatability in repositioning has to be guaranteed by a parallel manipulator, performing an alignment procedure mainly along 5 axes. Dynamics and control criteria with a feed forward chain to compensate for vibration forces and feedback chain for tracking procedure are hereafter presented.
Opto-mechanical design of the G-CLEF flexure control camera system
Author(s):
Jae Sok Oh;
Chan Park;
Jihun Kim;
Kang-Min Kim;
Moo-Young Chun;
Young Sam Yu;
Sungho Lee;
Jakyoung Nah;
Sung-Joon Park;
Andrew Szentgyorgyi;
Stuart McMuldroch;
Timothy Norton;
William Podgorski;
Ian Evans;
Mark Mueller;
Alan Uomoto;
Jeffrey Crane;
Tyson Hare
Show Abstract
The GMT-Consortium Large Earth Finder (G-CLEF) is the very first light instrument of the Giant Magellan Telescope (GMT). The G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. KASI (Korea Astronomy and Space Science Institute) is responsible for Flexure Control Camera (FCC) included in the G-CLEF Front End Assembly (GCFEA). The FCC is a kind of guide camera, which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within the GCFEA. The FCC consists of five optical components: a collimator including triple lenses for producing a pupil, neutral density filters allowing us to use much brighter star as a target or a guide, a tent prism as a focus analyzer for measuring the focus offset at the fiber mirror, a reimaging camera with three pair of lenses for focusing the beam on a CCD focal plane, and a CCD detector for capturing the image on the fiber mirror. In this article, we present the optical and mechanical FCC designs which have been modified after the PDR in April 2015.
Polishing test of a poly-crystal calcium fluoride lens: toward the development of TMT WFOS
Author(s):
Shinobu Ozaki;
Satoshi Miyazaki;
Toshihiro Tsuzuki;
Yoko Tanaka
Show Abstract
Wide-Field Optical Spectrograph (WFOS) is one of the first-light instruments of Thirty Meter Telescope (TMT), and developed in an international collaboration led by University of California Santa Cruz. It covers the wavelength range from 310 nm to 1 μm which is divided at around 550 nm by a dichroic mirror. Calcium Fluoride (CaF2) is very useful to reduce aberration and has good transmittance even at 310 nm. Because a large mono-crystal CaF2 is difficult to be manufactured, we might have to use a poly-crystal CaF2. Comparing a mono-crystal, the poly-crystal is expected to have worse optical index homogeneity and larger surface figure error after polishing. Those effects on an image quality are unclear. To verify those effects, we conducted a polishing test of a small poly-crystal CaF2 lens as a first step. As a result, we found figure error around the boundary. The figure error is ~139 nm PV and ~26 nm RMS. Comparing a Zemax simulation, it is confirmed that the figure error does not have significant effect on the image quality.
The MANIFEST prototyping design study
Author(s):
Jonathan S. Lawrence;
Sagi Ben-Ami;
David M. Brown;
Rebecca A. Brown;
Scott Case;
Steve Chapman;
Vladimir Churilov;
Matthew Colless;
Robert Content;
Darren Depoy;
Ian Evans;
Tony Farrell;
Michael Goodwin;
George Jacoby;
Urs Klauser;
Kyler Kuehn;
Nuria P. F. Lorente;
Slavko Mali;
Jennifer Marshall;
Rolf Muller;
Vijay Nichani;
Naveen Pai;
Travis Prochaska;
Will Saunders;
Luke Schmidt;
Keith Shortridge;
Nicholas F. Staszak;
Andrew Szentgyorgyi;
Julia Tims;
Minh V. Vuong;
Lewis G. Waller;
Ross Zhelem
Show Abstract
MANIFEST is a facility multi-object fibre system for the Giant Magellan Telescope, which uses ‘Starbug’ fibre positioning robots. MANIFEST, when coupled to the telescope’s planned seeing-limited instruments, GMACS, and G-CLEF, offers access to: larger fields of view; higher multiplex gains; versatile reformatting of the focal plane via IFUs; image-slicers; and in some cases higher spatial and spectral resolution. The Prototyping Design Study phase for MANIFEST, nearing completion, has focused on developing a working prototype of a Starbugs system, called TAIPAN, for the UK Schmidt Telescope, which will conduct a stellar and galaxy survey of the Southern sky. The Prototyping Design Study has also included work on the GMT instrument interfaces. In this paper, we outline the instrument design features of TAIPAN, highlight the modifications that will be necessary for the MANIFEST implementation, and provide an update on the MANIFEST/instrument interfaces.
WEBSIM-COMPASS: a new generation scientific instrument simulator for the E-ELT
Author(s):
M. Puech;
Y. Yang;
I. Jégouzo;
O. Marchal;
K. Disseau;
M. Paillous;
M. Rodrigues;
S. Taburet;
Y. Clénet;
D. Gratadour;
H. Flores;
F. Hammer
Show Abstract
We present a new scientific instrument simulator dedicated to the E-ELT named WEBSIM-COMPASS, and developed in the frame of the COMPASS project. This simulator builds on the previous series of WEBSIM simulators developed during the ESO E-ELT Design Reference Mission and Instrument Phase A studies. The WEBSIM-COMPASS observations simulator consists in a web interface coupled to an IDL code, which allows the user to perform end-to-end simulations of all E-ELT optical/NIR imagers and spectrographs foreseen for the future 39m European Extremely Large Telescope, i.e., MICADO, HARMONI, and MOSAIC. The simulation pipeline produces fake simulations in FITS format that mimic the result of a data reduction pipeline with perfectly extracted/reduced data. We give a functional description of this new simulator, emphasizing the new functionalities and current developments, and present science cases simulated used as test cases.
Preliminary optical design for the common fore optics of METIS
Author(s):
Tibor Agócs;
Bernhard R. Brandl;
Rieks Jager;
Felix Bettonvil;
Gabby Aitink-Kroes;
Lars Venema;
Matthew Kenworthy;
Olivier Absil;
Thomas Bertram
Show Abstract
METIS is the Mid-infrared E-ELT Imager and Spectrograph, which will provide outstanding observing capabilities, focusing on high angular and spectral resolution. It consists of two diffraction-limited imagers operating in the LM and NQ bands respectively and an IFU fed diffraction-limited high-resolution (R=100,000) LM band spectrograph. These science subsystems are preceded by the common fore optics (CFO), which provides the following essential functionalities: calibration, chopping, image de-rotation, thermal background and stray light reduction. We show the evolution of the CFO optical design from the conceptual design to the preliminary optical design, detail the optimization steps and discuss the necessary trade-offs.
Preliminary design study of the integral field unit for the E-ELT Harmoni instrument
Author(s):
J. Kosmalski;
M. Tecza;
I. Bryson;
F. Clarke;
D. Freeman;
M. Loupias;
J. E. Migniau;
A. Remillieux;
N. A. Thatte
Show Abstract
HARMONI is a visible and near-infrared (0.47 to 2.45 μm) integral field spectrograph over a range of resolving powers from R~3000 to R~20000. We will present in this paper, the different concepts of the HARMONI Integral Field Unit that makes the link between HARMONI Preoptics and the 4 Spectrographs. It is composed of a field splitter/relay system and an image slicer that creates from a rectangular Field of View a very long (532mm) pseudo-slit for each spectrograph. HARMONI is also considering a separate visible spectrograph and we present a possible image slicer for this option.
Development of cryogenic components based on COTS parts for the HARMONI instrument
Author(s):
José V. Gigante;
Elvio Hernández;
Luis F. Rodríguez-Ramos;
Cristian Estévez;
Antonio F. Moreno;
Begoña Garcia-Lorenzo;
José M. Herreros;
Evencio Mediavilla;
Ian Bryson;
Fraser Clarke;
Niranjan Thatte
Show Abstract
HARMONI is an integral field spectrograph working at visible and near-infrared wavelengths. The instrument will be part of the first-light complement at the E-ELT. The IAC is in charge of several work packages and the design of two important components is ongoing: A 'Cryogenic Pupil Mask Rotator' based on a direct drive brushless motor, and a 'Cryogenic Fast Shutter' based on voice coil. One of the main goals of these developments is the use of COTS (Commercial-Off-The-Shelf) parts since their use will reduce costs and short the schedule. Nevertheless, the application of COTS parts in cryo-vacuum is often very difficult and represents a technological challenge.
Novel instrument concepts for characterizing directly imaged exoplanets
Author(s):
Christoph U. Keller
Show Abstract
Current high-contrast exoplanet imagers are optimized to find new exoplanets; they minimize diffracted starlight in a large area around a star. I present four novel instrumental approaches that are optimized to characterize these discoveries by minimizing starlight in a small area around the known location of an exoplanet: 1) coronagraphs that remove virtually all starlight over an octave in wavelength while transmitting more than 90% of the exoplanet signal; 2) holographic wavefront sensors that measure aberrations in the science focal plane; 3) ultra-fast adaptive optics systems that minimize these aberrations; and 4) direct minimization of the remaining starlight. By integrating these technologies with a high spectral- resolution, integral-field spectrograph that can resolve the Doppler shift and the polarization difference between the starlight and the reflected light from the exoplanet, it will be possible to determine the atmospheric composition, temperature and velocity structures of exoplanets and their spin rotation rate and orbital velocity. This will ultimately allow the upcoming extremely large telescopes to characterize rocky exoplanets in the habitable zone to look for signatures of life.
Simulated observations of high-redshift galaxies with the HARMONI spectrograph for the European Extremely Large Telescope
Author(s):
Sarah Kendrew;
Simon Zieleniewski;
Ryan C. W. Houghton;
Niranjan Thatte;
Julien Devriendt;
Matthias Tecza;
Fraser Clarke;
Kieran O'Brien;
Boris Häußler
Show Abstract
We show the results of a study into the performance of the E-ELT integral field spectrograph HARMONI for observations of galaxies at 2 < z < 4. Using the instrument simulation pipeline HSIM, we performed mock observations of galaxies in this redshift range using two different methods: (i) passive galaxies modeled with simple analytical spatial profiles and star formation histories; and (ii) a single z = 3 galaxy extracted from a high-resolution cosmological simulation, with a more complex and physically representative morphology and star formation history. We describe the software tools developed to convert the simulation data into a spectral cube containing the spatial and spectral properties of the galaxy’s light. From the mock observations we estimate how well the intrinsic properties of the galaxy can be recovered using commonly used analysis tools. The HSIM pipeline also allows us to study observational biases and their likely impact on the data. We discuss the implications of the project for the future science with HARMONI in the critical redshift regime for mass assembly in galaxies.
The optical design of the G-CLEF Spectrograph: the first light instrument for the GMT
Author(s):
Sagi Ben-Ami;
Harland Epps;
Ian Evans;
Mark Mueller;
William Podgorski;
Andrew Szentgyorgyi
Show Abstract
The GMT-Consortium Large Earth Finder (G-CLEF), the first major light instrument for the GMT, is a fiber-fed, high-resolution echelle spectrograph. In the following paper, we present the optical design of G-CLEF. We emphasize the unique solutions derived for the spectrograph fiber-feed: the Mangin mirror that corrects the cylindrical field curvature, the implementation of VPH grisms as cross dispersers, and our novel solution for a multi-colored exposure meter. We describe the spectrograph blue and red cameras comprised of 7 and 8 elements respectively, with one aspheric surface in each camera, and present the expected echellogram imaged on the instrument focal planes. Finally, we present ghost analysis and mitigation strategy that takes into account both single reflection and double reflection back scattering from various elements in the optical train.
The Infrared Imaging Spectrograph (IRIS) for TMT: the ADC optical design
Author(s):
Andrew C. Phillips;
Ryuji Suzuki;
James E. Larkin;
Anna M. Moore;
Yutaka Hayano;
Toshihiro Tsuzuki;
Shelley A. Wright
Show Abstract
We present the current optical design for the IRIS Atmospheric Dispersion Corrector (ADC). The ADC is designed for residual dispersions less than ~1 mas across a given passband at elevations of 25 degrees. Since the last report, the area of the IRIS Imager has increased by a factor of four, and the pupil size has increased from 75 to 90mm, both of which contribute to challenges with the design. Several considerations have led to the current design: residual dispersion, amount of introduced distortion, glass transmission, glass availability, and pupil displacement. In particular, it was found that there are significant distortions that appear (two different components) that can lead to image blur over long exposures. Also, pupil displacement increases the wave front error at the imager focus. We discuss these considerations, discuss the compromises, and present the final design choice and expected performance.
The opto-mechanical design of the GMT-Consortium Large Earth Finder (G-CLEF)
Author(s):
Mark Mueller;
Andrew Szentgyorgyi;
Daniel Baldwin;
Jacob Bean;
Sagi Ben-Ami;
Patricia Brennan;
J. Budynkiewicz;
Moo-Yung Chun;
Jeffrey D. Crane;
Harland Epps;
Ian Evans;
Janet Evans;
Jeff Foster;
Anna Frebel;
Thomas Gauron;
Alex Glenday;
Tyson Hare;
Bi-Ho Jang;
Jeong-Gyun Jang;
Andreas Jordan;
Jihun Kim;
Kang-Min Kim;
Claudia Mendes de Oliveira;
Mercedes Lopez-Morales;
Kenneth McCracken;
Stuart McMuldroch;
Joseph Miller;
Jae Sok Oh;
Cem Onyuksel;
Mark Ordway;
Chan Park;
Sung-Joon Park;
Charles Paxson;
David Phillips;
David Plummer;
William Podgorski;
Andreas Seifahrt;
Joao Steiner;
Alan Uomoto;
Ronald Walsworth;
Young-Sam Yu
Show Abstract
The GMT-Consortium Large Earth Finder (G-CLEF) is a fiber-fed, optical echelle spectrograph selected as the first light instrument for the Giant Magellan Telescope (GMT) now under construction at the Las Campanas Observatory in Chile. G-CLEF has been designed to be a general-purpose echelle spectrograph with precision radial velocity (PRV) capability for exoplanet detection. The radial velocity (RV) precision goal of G-CLEF is 10 cm/sec, necessary for detection of Earth-sized exoplanets. This goal imposes challenging stability requirements on the optical mounts and the overall spectrograph support structures especially when considering the instrument’s operational environment. The accuracy of G-CLEF’s PRV measurements will be influenced by minute changes in temperature and ambient air pressure as well as vibrations and micro gravity-vector variations caused by normal telescope slewing. For these reasons we have chosen to enclose G-CLEF’s spectrograph in a well-insulated, vibration isolated vacuum chamber in a gravity invariant location on GMT’s azimuth platform. Additional design constraints posed by the GMT telescope include: a limited space envelope, a thermal emission ceiling, and a maximum weight allowance. Other factors, such as manufacturability, serviceability, available technology and budget are also significant design drivers. All of the above considerations must be managed while ensuring performance requirements are achieved. In this paper, we discuss the design of G-CLEF’s optical mounts and support structures including the choice of a low coefficient of thermal expansion (CTE) carbon-fiber optical bench to minimize the system’s sensitivity to thermal soaks and gradients. We discuss design choices made to the vacuum chamber geared towards minimize the influence of daily ambient pressure variations on image motion during observation. We discuss the design of G-CLEF’s insulated enclosure and thermal control systems which will maintain the spectrograph at milli-Kelvin level stability while simultaneously limiting thermal emissions into the telescope dome. Also discussed are micro gravity-vector variations caused by normal telescope slewing, their uncorrected influence on image motion, and how they are dealt with in the design. Finally, we discuss G-CLEF’s front-end assembly and fiber-feed system as well as other interface challenges presented by the telescope, enclosure and neighboring instrumentation.
Design and analysis of the NFIRAOS thermal optics enclosure
Author(s):
Joeleff Fitzsimmons;
David Andersen;
Jenny Atwood;
Peter Byrnes;
Glen Herriot;
Alexis Hill;
Kei Szeto
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The Narrow Field InfraRed Adaptive Optics System (NFIRAOS) will be the first-light facility adaptive optics system for the Thirty Meter Telescope (TMT). In order to meet the optical performance and stability specifications essential to leveraging the extraordinary capabilities of the TMT, all of the optical components within NFIRAOS will be protected within a large thermally-controlled optics enclosure (ENCL). Among the many functions performed by the ENCL, the most critical functions include providing a highly stable, light-tight, cold, dry environment maintained at 243±0.5 K for the NFIRAOS opto-mechanical sub-systems and supporting TABL structure. Although the performance of the ENCL during the science operation of NFIRAOS is critical, the maximum thermal loading will be defined by the cooldown/ warm-up cycle which must be accomplished within a time-frame that will minimize the on-sky operational impact due to daytime maintenance work. This study describes the thermal/mechanical design development and supporting analyses (analytical and finite element analyses (FEA)) completed during the preliminary design phase and through the current progression of the ENCL final design phase. The walls of the ENCL consist of interlocking, multilayered, thermally insulated panels, which are supported by an externally located structural framework which attaches to the NFIRAOS Instrument Support Structure. The regulation of the interior ENCL wall surface temperature to within ±0.5 K requires that the heat flux into the interior of NFIRAOS be eliminated by cooling a thermal conduction plate embedded between multiple layers of insulation. The thermal design of the enclosure was evaluated for both steady-state (SS) performance and transient performance (cool-down and warm-up cycles). The transient analysis utilizes a hybrid of a one-dimensional thermal network approach combined with three-dimensional conjugate heat transfer analyses of explicit opto-mechanical components within the ENCL. Many design-parameter combinations were evaluated to determine the performance impact of cooling power and transient temperature profiles. The results derived from the analyses of these design iterations indicate the multi-layer enclosure wall design will meet all thermal requirements. During SS operation, the interior temperature variation is within ±0.5 K of the target operational temperature, while the heat influx from the exterior TMT environment is 1528 W (extracted by the embedded cold plate). The transient cool-down cycle will take approximately 15 hours to complete and requires the in-situ air handling units to deliver 14KW of cooling power (derated for the TMT site conditions) throughout the interior space of the NFIRAOS ENCL.
High-contrast imaging with METIS
Author(s):
Matthew A. Kenworthy;
Olivier Absil;
Tibor Agócs;
Eric Pantin;
Sascha Quanz;
Remko Stuik;
Frans Snik;
Bernhard Brandl
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The Mid-infrared E-ELT Imager and Spectrograph (METIS) for the European Extremely Large Telescope (E-ELT) consists of diffraction-limited imagers that cover 3 to 14 microns with medium resolution (R ~ 5000) long slit spectroscopy, and an integral field spectrograph for high spectral resolution spectroscopy (R ~ 100,000) over the L and M bands. One of the science cases that METIS addresses is the characterization of faint circumstellar material and exoplanet companions through imaging and spectroscopy. We present our approach for high contrast imaging with METIS, covering diffraction suppression with coronagraphs, the removal of slowly changing optical aberrations with focal plane wavefront sensing, interferometric imaging with sparse aperture masks, and observing strategies for both the imagers and IFU image slicers.
Generalized atmospheric dispersion correctors for Thirty Meter Telescope
Author(s):
Brian M. Sutin
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The Thirty Meter Telescope (TMT) is unbaffled and has stability requirements tighter than the previous generation of 10- m class telescopes, leading to tougher requirements on atmospheric dispersion correctors (ADCs). Since instruments are internally baffled, ADCs may no longer shift the position of the telescope exit pupil. Designs that control pupil position are explored.
The Infrared Imaging Spectrograph (IRIS) for TMT: prototyping of cryogenic compatible stage for the imager
Author(s):
Fumihiro Uraguchi;
Yoshiyuki Obuchi;
Bungo Ikenoue;
Sakae Saito;
Ryuji Suzuki;
Yutaka Hayano
Show Abstract
The IRIS Imager requires opt-mechanical stages which are operable under vacuum and cryogenic environment. Also the stage for the IRIS Imager is required to survive for 10 years without maintenance. To achieve the development goal, we decided prototyping of a two axis stage with 80 mm clear aperture. The prototype was designed as a double-deck stage, upper rotary stage and lower linear stage. Most of components are selected to take advantage of heritage from existing astronomical instruments. In contrast, mechanical components with lubricants such as bearings, linear motion guides and ball screws were modified to survive cryogenic environment. The performance proving test was carried out to evaluate errors such as wobbling, rotary and linear positioning error. Also durability test under anticipated load condition has been conducted. In this article, we report the detail of mechanical design, fabrication, performance and durability of the prototype.
The Infrared Imaging Spectrograph (IRIS) for TMT: multi-tiered wavefront measurements and novel mechanical design
Author(s):
Jennifer Dunn;
David Andersen;
Edward Chapin;
Vlad Reshetov;
Ramunas Wierzbicki;
Glen Herriot;
Dean Chalmer;
Victor Isbrucker;
James E. Larkin;
Anna M. Moore;
Ryuji Suzuki
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The InfraRed Imaging Spectrograph (IRIS) will be the first light adaptive optics instrument on the Thirty Meter Telescope (TMT). IRIS is being built by a collaboration between Caltech, the University of California, NAOJ and NRC Herzberg. In this paper we present novel aspects of the Support Structure, Rotator and On-Instrument Wavefront Sensor systems being developed at NRC Herzberg. IRIS is suspended from the bottom port of the Narrow Field Infrared Adaptive Optics System (NFIRAOS), and provides its own image de-rotation to compensate for sidereal rotation of the focal plane. This arrangement is a challenge because NFIRAOS is designed to host two other science instruments, which imposes strict mass requirements on IRIS. As the mechanical design of all elements has progressed, we have been tasked with keeping the instrument mass under seven tonnes. This requirement has resulted in a mass reduction of 30 percent for the support structure and rotator compared to the most recent IRIS designs. To accomplish this goal, while still being able to withstand earthquakes, we developed a new design with composite materials. As IRIS is a client instrument of NFIRAOS, it benefits from NFIRAOS’s superior AO correction. IRIS plays an important role in providing this correction by sensing low-order aberrations with three On-Instrument Wavefront Sensors (OIWFS). The OIWFS consists of three independently positioned natural guide star wavefront sensor probe arms that patrol a 2-arcminute field of view. We expect tip-tilt measurements from faint stars within the IRIS imager focal plane will further stabilize the delivered image quality. We describe how the use of On-Detector Guide Windows (ODGWs) in the IRIS imaging detector can be incorporated into the AO correction. In this paper, we present our strategies for acquiring and tracking sources with this complex AO system, and for mitigating and measuring the various potential sources of image blur and misalignment due to properties of the mechanical structure and interfaces.
A concept for seeing-limited near-IR spectroscopy on the Giant Magellan Telescope
Author(s):
Robert A. Simcoe;
Gábor Fűrész;
Mark Egan;
Timothy Hellickson;
Andrew Malonis
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We present a simple seeing-limited IR spectrometer design for the Giant Magellan Telescope, with continuous R = 6000 coverage from 0.87-2.50 microns for a 0:7” slit. The instrument's design is based on an asymmetric white pupil echelle layout, with dichroics splitting the optical train into yJ, H, and K channels after the pupil transfer mirror. A separate low-dispersion mode offers single-object R ~ 850 spectra which also cover the full NIR bandpass in each exposure. Catalog gratings and H2RG detectors are used to minimize cost, and only two cryogenic rotary mechanisms are employed, reducing mechanical complexity. The instrument dewar occupies an envelope of 1:8×1:5×1:2 meters, satisfying mass and volume requirements for GMT with comfortable margin. We estimate the system throughput at ~ 35% including losses from the atmosphere, telescope, and instrument (i.e. all coatings, gratings, and sensors). This optical efficiency is comparable to the FIRE spectrograph on Magellan, and we have specified and designed fast cameras so the GMT instrument will have an almost identical pixel scale as FIRE. On the 6.5 meter Magellan telescopes, FIRE is read-noise limited in the y and J bands, similar to other existing near-IR spectrometers and also to JWST/NIRSPEC. GMT's twelve-fold increase in collecting area will therefore offer gains in signal-to-noise per exposure that exceed those of moderate resolution optical instruments, which are already sky-noise limited on today's telescopes. Such an instrument would allow GMT to pursue key early science programs on the Epoch of Reionization, galaxy formation, transient astronomy, and obscured star formation environments prior to commissioning of its adaptive optics system. This design study demonstrates the feasibility of developing relatively affordable spectrometers at the ELT scale, in response to the pressures of joint funding for these telescopes and their associated instrument suites.
Optical design of the post-focal relay of MAORY
Author(s):
M. Lombini;
A. De Rosa;
P. Ciliegi;
F. Cortecchia;
E. Diolaiti;
Mauro Patti;
M. Bonaglia;
L. Busoni;
V. De Caprio;
S. Esposito;
P. Feautrier;
P. Rabou;
M. Riva;
E. Stadler
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The Multi Conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope is planned to be located on the straight-through port of the telescope Nasmyth platform and shall re-image the telescope focal plane to a wide field camera (MICADO) and a possible future second instrument. By means of natural and artificial (laser) reference sources for wavefront sensing, and of deformable mirrors for wavefront correction, MAORY shall be able to compensate the wavefront disturbances affecting the scientific observations, achieving high Strehl ratio and high sky coverage. A trade-off study among different design options has been carried out addressing optical performance at the exit ports (wave front error, field distortion, throughput), structure stability, interface constraints (mass, size, location and accessibility of the two client instruments), and the overall adaptive optics performance. We discuss the baseline configuration of the opto-mechanical design.
Wavelength dependence of star images formed by large ground-based telescopes including ELTs
Author(s):
T. Stewart McKechnie
Show Abstract
Star image appearance in large ground-based telescopes is determined by the properties of the Optical Path Difference (OPD) fluctuation associated with the image-forming wave potions collected by the telescope aperture. The principal properties are the root mean square (rms) OPD fluctuation and the autocorrelation function of the OPD fluctuation. The OPD properties ultimately depend on the combined effects of turbulence in the atmospheric path, the fixed aberrations of the telescope and, if appropriate, the corrective effects of Adaptive Optics (AO). The equations given in this paper relating star image properties to the OPD properties (and also the inverse relations) apply to all large ground-based reflector telescopes, including ELTs. They apply equally to telescopes with and without AO. The OPD properties can be obtained directly from an image of an unresolved star. This image represents the intensity Point Spread Function (PSF) corresponding to the entire end-to-end imaging path. To obtain the full OPD information compliment, however, the image must be formed at a wavelength that delivers the most general type of star image: a core and halo image. Once the OPD properties have been obtained from such an image, the intensity PSF for the telescope/atmosphere/AO combination can immediately be calculated for any other wavelengths of interest in the extended optical wavelength range, 0.3 μm – 1000 μm. There are numerous applications for the mathematical relationships set out in this paper, including characterization of atmospheric paths, assessment of telescope/AO imaging performance, establishing wave front tolerances for ELTs and other large ground-based telescopes, and the rapid identification of sweetspot wavelength regions where highest resolution is achieved and star images attain maximum central intensity.
Flowdown of the TMT astrometry error budget(s) to the IRIS design
Author(s):
Matthias Schöck;
David Andersen;
John Rogers;
Brent Ellerbroek;
Eric Chisholm;
Jennifer Dunn;
Glen Herriot;
James Larkin;
Anna Moore;
Ryuji Suzuki;
James Wincentsen;
Shelley Wright
Show Abstract
TMT has defined the accuracy to be achieved for both absolute and differential astrometry in its top-level requirements documents. Because of the complexities of different types of astrometric observations, these requirements cannot be used to specify system design parameters directly. The TMT astrometry working group therefore developed detailed astrometry error budgets for a variety of science cases. These error budgets detail how astrometric errors propagate through the calibration, observing and data reduction processes. The budgets need to be condensed into sets of specific requirements that can be used by each subsystem team for design purposes. We show how this flowdown from error budgets to design requirements is achieved for the case of TMT's first-light Infrared Imaging Spectrometer (IRIS) instrument.
The Infrared Imaging Spectrograph (IRIS) for TMT: optical design of IRIS imager with "co-axis double TMA"
Author(s):
Toshihiro Tsuzuki;
Ryuji Suzuki;
Hiroki Harakawa;
Bungo Ikenoue;
James Larkin;
Anna Moore;
Yoshiyuki Obuchi;
Andrew C. Phillips;
Sakae Saito;
Fumihiro Uraguchi;
James Wincentsen;
Shelley Wright;
Yutaka Hayano
Show Abstract
IRIS (InfraRed Imaging Spectrograph) is one of the first-generation instruments for the Thirty Meter Telescope (TMT). IRIS is composed of a combination of near-infrared (0.84-2.4 μm) diffraction limited imager and integral field spectrograph. To achieve near-diffraction limited resolutions in the near-infrared wavelength region, IRIS uses the advanced adaptive optics system NFIRAOS (Narrow Field Infrared Adaptive Optics System) and integrated on-instrument wavefront sensors (OIWFS). However, IRIS itself has challenging specifications. First, the overall system wavefront error should be less than 40 nm in Y, z, J, and H-band and 42 nm in K-band over a 34.0 × 34.0 arcsecond field of view. Second, the throughput of the imager components should be more than 42 percent. To achieve the extremely low wavefront error and high throughput, all reflective design has been newly proposed. We have adopted a new design policy called "Co-Axis double-TMA", which cancels the asymmetric aberrations generated by "collimator/TMA" and "camera/TMA" efficiently. The latest imager design meets all specifications, and, in particular, the wavefront error is less than 17.3 nm and throughput is more than 50.8 percent. However, to meet the specification of wavefront error and throughput as built performance, the IRIS imager requires both mirrors with low surface irregularity after high-reflection coating in cryogenic and high-level Assembly Integration and Verification (AIV). To deal with these technical challenges, we have done the tolerance analysis and found that total pass rate is almost 99 percent in the case of gauss distribution and more than 90 percent in the case of parabolic distribution using four compensators. We also have made an AIV plan and feasibility check of the optical elements. In this paper, we will present the details of this optical system.
