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- Front Matter: Volume 7735
- Instrument Overviews at Large Facilities
- Ground-based Optical Instruments I
- Ground-based Optical Instruments II
- Techniques and Components I
- Instrumentation and Techniques for Exoplanet Detection
- Ground-based Infrared Instruments I
- Ground-based Infrared Instruments II
- Techniques and Components II
- Airborne instrumentation
- Solar Instrumentation
- Instrumentation for ELTs I
- Instrumentation for ELTs II
- Instrumentation for ELTs III
- Poster Session I
- Poster Session II
Front Matter: Volume 7735
Front Matter: Volume 7735
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This PDF file contains the front matter associated with SPIE Proceedings Volume 7735, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Instrument Overviews at Large Facilities
Advances in instrumentation at the W. M. Keck Observatory
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In this paper we describe both recently completed instrumentation projects and our current development efforts in the
context of the Observatory's science driven strategic plan which seeks to address key questions in observational
astronomy for extra-galactic, Galactic, and planetary science with both seeing limited capabilities and high angular
resolution adaptive optics capabilities. This paper will review recently completed projects as well as new instruments in
development including MOSFIRE, a near IR multi-object spectrograph nearing completion, a new seeing limited
integral field spectrograph for the visible wavelength range called the Keck Cosmic Web Imager, and the Keck Next
Generation Adaptive Optics facility and its first light science instrument DAVINCI.
ESO instrumentation for the La Silla/Paranal Observatory
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The first-generation instrument development programme for the VLT/I has now come to a close. The delivered
instruments which have served the astronomical community since first light at Paranal in 1998, have provided
astronomers with general purpose capabilities covering the available wavelength range from the UV to mid infrared. The
second-generation programme has now begun with delivery of X-shooter, and a further six new instruments (SPHERE,
MUSE, KMOS, ESPRESSO, GRAVITY, MATISSE) are under construction, marking a transition to more specialised
scientific capabilities designed for a more limited but very ambitious set of science goals. In addition, instrumentation at
La Silla telescopes continues to be effective in producing scientific results, especially through the planet-finder HARPS
on the 3.6m. Future plans should see a transfer of resources to E-ELT instrument construction while new instrument
development for the VLT will continue, but at a slower pace.
Instrumentation at the Subaru Telescope
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Developing new instruments and upgrading existing instruments has been an important aspect of Subaru telescope's
operation. Seven facility instruments and two visiting instruments are currently under use. Among them
HiCIAO, a coronagraphic imager combined with adaptive optics (AO188), has started its full operation in the 2nd
semester of 2009. We are using HiCIAO for a large program (SEEDS) to find new exo-planets and comprehend
planet formation from proto-planetary disks. To achieve higher contrast, a new coronagraph attachment with an
extreme AO (SCExAO) will be installed as a PI instrument. AO188 is also used with the IRCS in natural guide
star mode. Its laser guide star mode is currently commissioning. The Fibre multi-object spectrograph (FMOS),
which is comprised of 400 fibers placed at the prime focus and delivers 0.9-1.8um spectra, will be partly offered
to open use from mid 2010. Hyper Suprime-Cam, the wide-field upgrade (1.5 deg FoV) of the Suprime-Cam, is
under development for its first light in 2011. Development of an immersion grating has taken place for upgrading
the IRCS with a high-resolution infrared spectrograph.
Gemini Observatory instrumentation: a review of the past, present, and future on our 10th anniversary
Show abstract
The tenth anniversary of Gemini Observatory operation provides a convenient reference point to reflect on the past,
present, and future of the instrumentation program. The Observatory will soon meet a significant milestone: the last
batch of instruments from the first three generations of instrumentation development will be commissioned by the end of
2011. This will represent a revolution for Gemini-South, which will have a suite of new or upgraded, state of the art
instruments. Included in this suite will be extreme and multi-conjugate adaptive optics systems, new infrared imagers
and multi-object spectrographs, and state of the art CCD detectors. The Observatory is on the cusp of a new era with the
fourth generation of instrumentation. While the past represented building a whole new observatory, the future represents
renewal and reinvestment, with plans for a new high-resolution optical spectrograph, new acquisition and guide units,
upgraded and refurbished instruments, and improved methods for developing Gemini instrumentation.
An overview of instrumentation for the Large Binocular Telescope
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An overview of instrumentation for the Large Binocular Telescope is presented. Optical instrumentation includes
the Large Binocular Camera (LBC), a pair of wide-field (27 × 27) mosaic CCD imagers at the prime focus, and
the Multi-Object Double Spectrograph (MODS), a pair of dual-beam blue-red optimized long-slit spectrographs
mounted at the straight-through F/15 Gregorian focus incorporating multiple slit masks for multi-object spectroscopy
over a 6 field and spectral resolutions of up to 8000. Infrared instrumentation includes the LBT Near-IR
Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research (LUCIFER), a modular
near-infrared (0.9-2.5 μm) imager and spectrograph pair mounted at a bent interior focal station and designed
for seeing-limited (FOV: 4 × 4) imaging, long-slit spectroscopy, and multi-object spectroscopy utilizing cooled
slit masks and diffraction limited (FOV: 0.5 × 0.5) imaging and long-slit spectroscopy. Strategic instruments
under development for the remaining two combined focal stations include an interferometric cryogenic beam combiner
with near-infrared and thermal-infrared instruments for Fizeau imaging and nulling interferometry (LBTI)
and an optical bench near-infrared beam combiner utilizing multi-conjugate adaptive optics for high angular
resolution and sensitivity (LINC-NIRVANA). In addition, a fiber-fed bench spectrograph (PEPSI) capable of
ultra high resolution spectroscopy and spectropolarimetry (R = 40,000-300,000) will be available as a principal
investigator instrument. The availability of all these instruments mounted simultaneously on the LBT permits
unique science, flexible scheduling, and improved operational support. Over the past two years the LBC and the
first LUCIFER instrument have been brought into routine scientific operation and MODS1 commissioning is set
to begin in the fall of 2010.
Instrumentation suite at the MMT Observatory
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In the ten years since the converted 6.5m MMT was dedicated the observatory has built up an impressive
suite of instrumentation to compliment the three interchangeable secondary mirrors. This review paper
presents an up-to-date perspective on all the capabilities of our full range of instrumentation, highlighting
newly commissioned instruments (the MMT and Magellan InfraRed Spectrograph (MMIRS), an infrared
spectrograph) and new modes or upgrades for established instruments (such as; Red Channel, the MMT's
workhorse spectrograph, Hectochelle, an optical fiber-fed, multi-object spectrograph and the AO
instruments CLIO, a 5 micron camera and BLINC, a mid-infrared camera). The MMT's pioneering
adaptive secondary mirror can be used with both natural guide stars (NGS) or with a Rayleigh laser guide
star (LGS) system. The LGS has recently demonstrated wide-field partial compensation with ground layer
adaptive optics and here we present progress to date. Finally, we report on the start of a project to
investigate how the instrument suite has contributed to the science productivity the MMT over the last 10
years.
Ground-based Optical Instruments I
The MUSE second-generation VLT instrument
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Summary: The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field
spectrograph currently in manufacturing, assembly and integration phase. MUSE has a field of 1x1 arcmin2 sampled at
0.2x0.2 arcsec2 and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The
instrument is a large assembly of 24 identical high performance integral field units, each one composed of an advanced
image slicer, a spectrograph and a 4kx4k detector. In this paper we review the progress of the manufacturing and report
the performance achieved with the first integral field unit.
HERMES: revisions in the design for a high-resolution multi-element spectrograph for the AAT
Show abstract
The AAO is building an optical high resolution multi-object spectrograph for the AAT for Galactic Archaeology. The
instrument has undergone significant design revision over that presented at the 2008 Marseilles SPIE meeting. The
current design is a 4-channel VPH-grating based spectrograph providing a nominal spectral resolving power of 28,000
and a high-resolution mode of 45,000 with the use of a slit mask. The total spectral coverage is about 1000 Angstroms
for up to 392 simultaneous targets within the 2 degree field of view. Major challenges in the design include the
mechanical stability, grating and dichroic efficiencies, and fibre slit relay implementation. An overview of the current
design and discussion of these challenges is presented.
The multi-object double spectrographs for the Large Binocular Telescope
Show abstract
The Multi-Object Double Spectrographs (MODS) are two identical high-throughput optical low- to medium-resolution
CCD spectrometers being deployed at the Large Binocular Telescope (LBT). Operating in the 340-1000nm range, they
use a large dichroic to split light into separately-optimized red and blue channels that feature reflective collimators and
decentered Maksutov-Schmidt cameras with monolithic 8×3K CCD detectors. A parallel infrared laser closed-loop
image motion compensation system nulls spectrograph flexure giving it high calibration stability. The two MODS
instruments may be operated together with digital data combination as a single instrument giving the LBT an effective
aperture of 11.8-meter, or separately configured to flexibly use the twin 8.4-meter apertures. This paper describes the
properties and performance of the completed MODS1 instrument. MODS1 was delivered to LBT in May 2010 and is
being prepared for first-light in September 2010.
SITELLE: a wide-field imaging Fourier transform spectrometer for the Canada-France-Hawaii Telescope
Show abstract
We describe the concept of a new instrument for the Canada-France-Hawaii telescope (CFHT), SITELLE (Spectromètre
Imageur à Transformée de Fourier pour l'Etude en Long et en Large de raies d'Emission), as well as a science case and
a technical study of its preliminary design. SITELLE will be an imaging Fourier transform spectrometer capable of
obtaining the visible (350 nm - 950 nm) spectrum of every source of light in a field of view of 15 arcminutes, with 100%
spatial coverage and a spectral resolution ranging from R = 1 (deep panchromatic image) to R = 104 (for gas dynamics).
SITELLE will cover a field of view 100 to 1000 times larger than traditional integral field spectrographs, such as
GMOS-IFU on Gemini or the future MUSE on the VLT. It is a legacy from BEAR, the first imaging FTS installed on
the CFHT and the direct successor of SpIOMM, a similar instrument attached to the 1.6-m telescope of the Observatoire
du Mont-Mégantic in Québec. SITELLE will be used to study the structure and kinematics of HII regions and ejecta
around evolved stars in the Milky Way, emission-line stars in clusters, abundances in nearby gas-rich galaxies, and the
star formation rate in distant galaxies.
Performance and sensitivity of low-resolution spectrographs for LAMOST
Show abstract
The 16 low resolution spectrographs (LRS) have been successfully commissioned for the LAMOST. The LRS design
employs a dual-beamed and bench-mounted, with large-beamed, fast Schmidt cameras and Volume Phase Holographic
(VPH) transmission gratings. The design wavelength range is 370-900nm, at resolutions of R=1000and R=10000. Each
spectrograph is fed by 250 fibers with 320 micron in diameter (corresponding 3.3 arcsec), composed of one F/4 Schmidt
collimator, a dichroic beam-splitter, four VPH gratings, articulating Schmidt cameras that are optimized at blue band
(370-590 nm) and red band (570-900 nm), and field lens near the focal plane service as the vacuum window of CCD
detector cryogenic head. In this paper, we present the testing result of the LRS on the image quality, spectra resolution,
efficiency and observing spectra.
Status of the dark energy survey camera (DECam) project
Show abstract
The Dark Energy Survey Collaboration is building the Dark Energy Camera (DECam), a 3 square degree, 520
Megapixel CCD camera which will be mounted on the Blanco 4-meter telescope at CTIO. DECam will be used to
perform the 5000 sq. deg. Dark Energy Survey with 30% of the telescope time over a 5 year period. During the
remainder of the time, and after the survey, DECam will be available as a community instrument. Construction of
DECam is well underway. Integration and testing of the major system components has already begun at Fermilab and
the collaborating institutions.
Science with GYES: a multifibre high-resolution spectrograph for the prime focus of the Canada-France-Hawaii Telescope
P. Bonifacio,
F. Arenou,
C. Babusiaux,
et al.
Show abstract
We present the scientific motivations for GYES: a high multiplex (of the order of several hundred), high resolution
(about 20 000), spectrograph to be placed at the prime focus of the CFHT. The main purpose of such an
instrument is to conduct a spectroscopic survey complementary to the Gaia mission. The final Gaia catalogue
(expected around 2020) will provide accurate distances, proper motions and spectrophotometry for all the stars
down to a magnitude of 20. The spectroscopic instrument on board the Gaia satellite will provide intermediate
resolution (R=11 500) spectra for stars down to the 17th magnitude. For the fainter stars there will be no radial
velocity information. For all the stars the chemical information will be limited to a few species. A multifibre
spectrograph at the prime focus of the CFHT will be able to provide the high resolution spectra for stars fainter
than 13th magnitude, needed to obtain both accurate radial velocities and detailed chemical abundances. The possible use of GYES will not be limited to Gaia complementary surveys and we here describe the potentialities
of such an instrument. We describe here how the scientific drivers are translated into technical requirements.
The results of our on-going feasibility study are described in an accompanying poster.
ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations
Show abstract
ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the
efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESO's
VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity
precision will be improved to reach cm/s level. Thanks to its characteristics and the ability of combining
incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in various fields of astronomy. The
main scientific objectives will be the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby
G to M-dwarfs, and the analysis of the variability of fundamental physical constants. We will present the ambitious
scientific objectives, the capabilities of ESPRESSO, and the technical solutions of this challenging project.
The WIYN one degree imager: project update 2010
Show abstract
The One Degree Imager will be the future flagship instrument at the WIYN 3.5m observatory, once commissioned in
2011. With a 1 Gigapixel focal plane of Orthogonal Transfer Array CCD devices, ODI will be the most advanced optical
imager with open community access in the Northern Hemisphere. In this talk we will summarize the progress since the
last presentation of ODI at the SPIE 2008 meeting, focusing on optics procurement, instrument assembly and testing, and
detector operations.
Ground-based Optical Instruments II
Design, performance, and early results from extremely high Doppler precision instruments in a global network
Show abstract
We report design, performance and early results from two of the Extremely High Precision Extrasolar
Planet Tracker Instruments (EXPERT) as part of a global network for hunting for low mass planets in the
next decade. EXPERT is a combination of a thermally compensated monolithic Michelson interferometer
and a cross-dispersed echelle spectrograph for extremely high precision Doppler measurements for nearby
bright stars (e.g., 1m/s for a V=8 solar type star in 15 min exposure). It has R=18,000 with a 72 micron
slit and a simultaneous coverage of 390-694 nm. The commissioning results show that the instrument has
already produced a Doppler precision of about 1 m/s for a solar type star with S/N~100 per pixel. The
instrument has reached ~4 mK (P-V) temperature stability, ~1 mpsi pressure stability over a week and a
total instrument throughput of ~30% at 550 nm from the fiber input to the detector. EXPERT also has a
direct cross-dispersed echelle spectroscopy mode fed with 50 micron fibers. It has spectral resolution of
R=27,000 and a simultaneous wavelength coverage of 390-1000 nm.
'Imaka: a one-degree high-resolution imager for the Canada-France-Hawaii Telescope
Show abstract
The 'Imaka project is a high-resolution wide-field imager proposed for the Canada-France-Hawaii telescope
(CFHT) on Mauna Kea. 'Imaka takes advantage of two features of the optical turbulence above Mauna Kea:
weak optical turbulence in the free-atmosphere and boundary layer turbulence which is highly confined within a
surface layer tens of meters thick and or the telescope enclosures. The combination of the two allows a groundlayer
adaptive optics system (GLAO) to routinely deliver an extremely-wide corrected field of view of one-degree
at an excellent free-atmosphere seeing limit at visible wavelengths. In addition, populating the focal-plane with
orthogonal-transfer CCDs provides a second level of image improvement on the free-atmosphere seeing and the
residual GLAO correction. The impact of such an instrument covers a broad range of science and is a natural
progression of CFHT's wide-field expertise.
Design and development of the 3.2 gigapixel camera for the Large Synoptic Survey Telescope
Show abstract
The Large Synoptic Survey Telescope (LSST) is a large aperture, wide-field facility designed to provide deep images of
half the sky every few nights. There is only a single instrument on the telescope, a 9.6 square degree visible-band
camera, which is mounted close to the secondary mirror, and points down toward the tertiary. The requirements of the
LSST camera present substantial technical design challenges. To cover the entire 0.35 to 1 μm visible band, the camera
incorporates an array of 189 over-depleted bulk silicon CCDs with 10 μm pixels. The CCDs are assembled into 3 x 3
"rafts", which are then mounted to a silicon carbide grid to achieve a total focal plane flatness of 15 μm p-v. The CCDs
have 16 amplifiers per chip, enabling the entire 3.2 Gigapixel image to be read out in 2 seconds. Unlike previous
astronomical cameras, a vast majority of the focal plane electronics are housed in the cryostat, which uses a mixed
refrigerant Joule-Thompson system to maintain a -100ºC sensor temperature. The shutter mechanism uses a 3 blade
stack design and a hall-effect sensor to achieve high resolution and uniformity. There are 5 filters stored in a carousel
around the cryostat and the auto changer requires a dual guide system to control its position due to severe space
constraints. This paper presents an overview of the current state of the camera design and development plan.
Optical design of the ESPRESSO spectrograph at VLT
Show abstract
ESPRESSO, a very high-resolution, high-efficiency, ultra-high stability, fiber-fed, cross-dispersed echelle spectrograph
located in the Combined-Coudé focus of the VLT, has been designed to detect exo-planets with unprecedented radial
velocity accuracies of 10 cm/sec over 20 years period. To increase spectral resolution, an innovative pupil slicing
technique has been adopted, based onto free-form optics. Anamorphism has been added to increase resolution while
keeping the physical size of the echelle grating within reasonable limits. Anamorphic VPH grisms will help to decrease
detector size, while maximizing efficiency and inter-order separation. Here we present a summary of the optical design
of the spectrograph and of expected performances.
VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope
Show abstract
The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical
spectrographs (arrayed as 75 units, each with a pair of spectrographs) fed by 33,600 fibers, each 1.5 arcsec diameter,
deployed over the 22 arcminute field of the upgraded 10 m Hobby-Eberly Telescope (HET). The goal is to deploy 96
units. 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 spectral surveys of large areas of sky. The
method of industrial replication, in which a relatively simple, inexpensive, unit spectrograph is copied in large numbers,
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-α emitting galaxies as tracers. The full VIRUS array is due to be deployed
in late 2011 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the
telescope. VIRUS and HET will open up wide field surveys of the emission-line universe for the first time. We present
the design, cost, and current status of VIRUS as it enters production, and review performance results from the VIRUS
prototype. We also present lessons learned from our experience designing for volume production and look forward to
the application of the VIRUS concept on future extremely large telescopes (ELTs).
The Keck Cosmic Web Imager
Show abstract
We are designing the Keck Cosmic Web Imager (KCWI) as a new facility instrument for the Keck II telescope at the
W. M. Keck Observatory (WMKO). KCWI is based on the Cosmic Web Imager (CWI), an instrument that has recently
had first light at the Hale Telescope. KCWI is a wide-field integral-field spectrograph (IFS) optimized for precision sky
limited spectroscopy of low surface brightness phenomena. KCWI will feature high throughput, and flexibility in field of
view (FOV), spatial sampling, bandpass, and spectral resolution. KCWI will provide full wavelength coverage (0.35 to
1.05 μm) using optimized blue and red channels. KCWI will provide a unique and complementary capability at WMKO
(optical band integral field spectroscopy) that is directly connected to one of the Observatory's strategic goals (faint
object, high precision spectroscopy), at a modest cost and on a competitive time scale, made possible by its simple
concept and the prior demonstration of CWI.
Techniques and Components I
PIMMS: photonic integrated multimode microspectrograph
Show abstract
We present the first integrated multimode photonic spectrograph, a device we call PIMMS #1. The device comprises
a set of multimode fibres that convert to single-mode propagation using a matching set of photonic lanterns. These
feed to a stack of cyclic array waveguides (AWGs) that illuminate a common detector. Such a device greatly reduces
the size of an astronomical instrument at a fixed spectroscopic resolution. Remarkably, the PIMMS concept is
largely independent of the telescope diameter, input focal ratio and entrance aperture - i.e. one size fits all! The
instrument architecture can also exploit recent advances in astrophotonics (e.g. OH suppression fibres). We present a
movie of the instrument's operation and discuss the advantages and disadvantages of this approach.
Hexabundles: first results
Show abstract
New multi-core imaging fibre bundles - hexabundles - being developed at the University of Sydney will provide
simultaneous integral field spectroscopy for hundreds of celestial sources across a wide angular field. These are a
natural progression from the use of single fibres in existing galaxy surveys. Hexabundles will allow us to address
fundamental questions in astronomy without the biases introduced by a fixed entrance aperture. We have begun
to consider instrument concepts that exploit hundreds of hexabundles over the widest possible field of view. To
this end, we have characterised the performance of a 61-core fully fused hexabundle and 5 unfused bundles with
7 cores each. All fibres in bundles have 100 micron cores. In the fused bundle, the cores are distorted from a
circular shape in order to achieve a higher fill fraction. The unfused bundles have circular cores and five different
cladding thicknesses which affect the fill fraction. We compare the optical performance of all 6 bundles and find
that the advantage of smaller interstitial holes (higher fill fraction) is outweighed by the increase in FRD, crosstalk
and the poor optical performance caused by the deformation of the fibre cores. Uniformly high throughput
and low cross-talk are essential for imaging faint astronomical targets with sufficient resolution to disentangle
the dynamical structure. Devices already under development will have 100-200 unfused cores, although larger
formats are feasible. The light-weight packaging of hexabundles is sufficiently flexible to allow existing robotic
positioners to make use of them.
The Cosmic Web Imager: an integral field spectrograph for the Hale Telescope at Palomar Observatory: instrument design and first results
Show abstract
We describe the Cosmic Web Imager (CWI), a UV-VIS integral eld spectrograph designed for the Hale 200"
telescope at the Palomar Observatory. CWI has been built specically for the observation of diuse radiation.
The instrument eld of view is 60"40" with spectral resolving power of R5000 and seeing limited spatial
resolution. It utilizes volume phase holographic gratings and is intended to cover the spectral range 3800A to
9500A with an instantaneous bandwidth of 450A. CWI saw rst light in July 2009, and conducted its rst
successful scientic observations in May 2010.
Engineering a highly segmented very wide-field spectrograph
Show abstract
The concept of segmenting the focal plane of an existing 8m class telescope in order to fill it with an array of several fast
cameras has been developed further and in this work the status of an engineering program aimed to produce a design
qualified for the construction, and to assess its cost estimates is presented. The original concept of just having simple
cameras with all identical optical components other than a pupil plane corrector to remove the fixed aberrations at the
off-axis field of a telescope has been extended to introduce a spectroscopic capability and to assess a trade-off between a
very large number (of the order of thousand) of cameras with a small single Field of View with a smaller number of
cameras able to compensate the aberration on a much larger Field of View with a combination of different optical
elements and different ways to mount and align them.
The scientific target of a few thousands multi-slit spectra over a Field of View of a few square degrees, combined with
the ambition to mount this on an existing 8m class telescope makes the scientific rationale of such an instrument a very
interesting one. In the paper we describe the different options for a possible optical design, the trade off between
variations on the theme of the large segmentation and we describe briefly the way this kind of instrument can handle a
multi-slit configuration. Finally, the feasibility of the components and a brief description of how the cost analysis is
being performed are given. Perspectives on the construction of this spectrograph are given as well.
The low-resolution imaging spectrograph red channel CCD upgrade: fully depleted, high-resistivity CCDs for Keck
Show abstract
A mosaic of two 2k x 4k fully depleted, high resistivity CCD
detectors was installed in the red channel of the Low Resolution
Imaging Spectrograph for the Keck-I Telescope in June, 2009 replacing
a monolithic Tektronix/SITe 2k x 2k CCD. These CCDs were fabricated
at Lawrence Berkeley National Laboratory (LBNL) and packaged and
characterized by UCO/Lick Observatory. Major goals of the detector
upgrade were increased throughput and reduced interference fringing
at wavelengths beyond 800 nm, as well as improvements in the
maintainability and serviceability of the instrument. We report on
the main features of the design, the results of optimizing detector
performance during integration and testing, as well as the
throughput, sensitivity and performance of the instrument as
characterized during commissioning.
High-resolution imaging and spectroscopy in the visible from large ground-based telescopes with natural guide stars
Show abstract
Near-diffraction limited imaging and spectroscopy in the visible on large (8-10 meter) class telescopes has proved to be
beyond the capabilities of current adaptive optics technologies, even when using laser guide stars. The need for high
resolution visible imaging in any part of the sky suggests that a rather different approach is needed. This paper describes
the results of simulations, experiments and astronomical observations that show that a combination of low order adaptive
optic correction using a 4-field curvature sensor and fast Lucky Imaging strategies with a photon counting CCD camera
systems should deliver 20-25 milliarcsecond resolution in the visible with reference stars as faint as 18.5 magnitude in I
band on large telescopes. Such an instrument may be used to feed an integral field spectrograph efficiently using
configurations that will also be described.
High-precision calibration of spectrographs using laser frequency combs
Show abstract
We present the first stringent tests of a novel calibration system based on a laser frequency comb (LFC) for radial
velocity measurements. The tests were obtained with the high resolution, optical HARPS spectrograph. Photon noise
limited repeatability of 9 cm s-1 was obtained, using only little more than one of 72 echelle orders. In the calibration
curve CCD inhomogeneities showed up and could be calibrated, which were undetectable with previous Th-Ar
calibrations. To obtain an even higher repeatability and lower residuals, a larger spectral bandwidth is necessary. An
improved version of the LFC is currently under development. The results of the latest tests will be presented.
A new method to quantitatively compare focal ratio degradation due to different end termination techniques
Show abstract
We investigate the FRD performance of a 150 μm core fibre for its suitability to the SIDE project.1 This work
builds on our previous work2 (Paper 1) where we examined the dependence of FRD on length in fibres with a
core size of 100 μm and proposed a new multi-component model to explain the results. In order to predict the
FRD characteristics of a fibre, the most commonly used model is an adaptation of the Gloge8model by Carrasco
and Parry3 which quantifies the the number of scattering defects within an optical bre using a single parameter,
d0. The model predicts many trends which are seen experimentally, for example, a decrease in FRD as core
diameter increases, and also as wavelength increases. However the model also predicts a strong dependence on
FRD with length that is not seen experimentally. By adapting the single fibre model to include a second fibre,
we can quantify the amount of FRD due to stress caused by the method of termination. By fitting the model to
experimental data we find that polishing the fibre causes a small increase in stress to be induced in the end of
the fibre compared to a simple cleave technique.
SPHERE IFS: the spectro differential imager of the VLT for exoplanets search
Show abstract
The SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars
and to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made
of an extreme-Adaptive Optics (AO) wavefront correction, a pupil tracker and diffraction suppression through a variety
of coronagraphs. At its back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the
Near Infrared (NIR) Y, J, H and Ks bands (0.95 - 2.32μm), and a high resolution polarization camera covers the optical
range (0.6 - 0.9 μm). The IFS is a low resolution spectrograph (R~50) working in the near IR (0.95-1.65 microns), an
ideal wavelength range for the detection of giant planet features. In our baseline design the IFU is a new philosophy
microlens array of about 145x145 elements designed to reduce as much as possible the cross talk when working at
diffraction limit. The IFU will cover a field of view of about 1.7 x 1.7 square arcsecs reaching a contrast of 10-7,
providing a high contrast and high spatial resolution "imager" able to search for planet well inside the star PSF.
Instrumentation and Techniques for Exoplanet Detection
Fiber-stabilized PSF for sub-m/s Doppler precision at Lick Observatory
Show abstract
The detection of Earth analogues requires extreme Doppler precision and long term stability in order to measure tiny reflex velocities in the host star. The PSF from the spectrometer should be slowly varying with temperature and pressure changes. However, variations in the illumination of the slit and of the spectrograph optics occur on time scales of seconds, primarily because of guiding errors, but also on timescales of minutes, because of changes in the focus or seeing. These variations yield differences in the PSF from observation to observation, which are currently limiting the Doppler precision. Here, we present the design of a low cost fiber optic feed, FINDS, used to stabilize the PSF of the Hamilton spectrograph of Lick observatory along with the first measurements that show dramatic improvement in stability.
High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM
Show abstract
In this paper, we present an original observational approach, which combines, for the first time, traditional
speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high
contrast (10-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet
filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the
2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect
L-type brown dwarf companions around a solar-type star with a contrast ▵I~12 at 2 and with no use of any
coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has
been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini,
Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and
disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some
perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge
this is the first time that high contrast considerations are included in optical speckle imaging approach.
Along the path towards extremely precise radial velocity measurements
Show abstract
In the last six years, thanks to the very high radial velocity precision of the HARPS spectrograph, it was possible to
detect 21 out of the 30 super-Earth (extrasolar planets masses below 20 times the mass of the Earth) discovered up to
date. The radial velocity precision of the instrument is estimated around 80 cm/s on a single measurement.
The main instrumental limitations are the wavelength calibration and the stability of the light injection. We address both
factors and present the results of recent tests on the HARPS spectrograph.
We have identified the laser frequency comb as the ideal wavelength calibrator, due to the width, density and flux of the
lines, and to its intrinsic stability. The results from the recent tests that we performed on HARPS are encouraging.
The accurate guiding of the telescope is critical to maintain a stable light distribution at the injection stage, where the
light is sent into the spectrograph entrance fiber. To pursue this goal we are testing a secondary guiding system which is
able to apply the guiding corrections twenty times faster than the primary guiding system.
The prototype design of most powerful exoplanet tracker based on LAMOST
Show abstract
Chinese national science project-LAMOST successfully received its official blessing in June, 2009. Its aperture is about
4m, and its focal plane of 1.75m in diameter, corresponding to a 5° field of view, can accommodate as many as 4000
optical fibers, and feed 16 multi-object low-medium resolution spectrometers (LRS). In addition, a new technique called
External Dispersed Interferometry (EDI) is successfully used to enhance the accuracy of radial velocity measurement by
heterodyning an interference spectrum with absorption lines. For further enhancing the survey power of LAMOST, a
major astronomical project, Multi-object Exoplanet Survey System (MESS) based on this advanced technique, is being
developed by Nanjing Institute of Astronomical Optics and Technology (NIAOT) and National Astronomical
Observatories of China (NAOC), and funded by Joint Fund of Astronomy, which is set up by National Natural Sciences
Foundation of China (NSFC) and Chinese Academy of Sciences (CAS). This system is composed of a multi-object fixed
delay Michelson interferometer (FDMI) and a multi-object medium resolution spectrometer (R=5000). In this paper, a
prototype design of FDMI is given, including optical system and mechanical structure.
High contrast stellar observations within the diffraction limit at the Palomar Hale telescope
Show abstract
We report on high-accuracy, high-resolution (< 20mas) stellar measurements obtained in the near infrared (
2.2 microns) at the Palomar 200 inch telescope using two elliptical (3m x 1.5m) sub-apertures located 3.4m
apart. Our interferometric coronagraph, known as the "Palomar Fiber Nuller" (PFN), is located downstream
of the Palomar adaptive optics (AO) system and recombines the two separate beams into a common singlemode
fiber. The AO system acts as a "fringe tracker", maintaining the optical path difference (OPD) between
the beams around an adjustable value, which is set to the central dark interference fringe. AO correction
ensures high efficiency and stable injection of the beams into the single-mode fiber. A chopper wheel and a fast
photometer are used to record short (< 50ms per beam) interleaved sequences of background, individual beam
and interferometric signals. In order to analyze these chopped null data sequences, we developed a new statistical
method, baptized "Null Self-Calibration" (NSC), which provides astrophysical null measurements at the 0.001
level, with 1 σ uncertainties as low as 0.0003. Such accuracy translates into a dynamic range greater than 1000:1
within the diffraction limit, demonstrating that the approach effectively bridges the traditional gap between
regular coronagraphs, limited in angular resolution, and long baseline visibility interferometers, whose dynamic
range is restricted to 100:1. As our measurements are extremely sensitive to the brightness distribution very
close to the optical axis, we were able to constrain the stellar diameters and amounts of circumstellar emission
for a sample of very bright stars. With the improvement expected when the PALM-3000 extreme AO system
comes on-line at Palomar, the same instrument now equipped with a state of the art low noise fast read-out near
IR camera, will yield 10-4 to 10-3 contrast as close as 30 mas for stars with K magnitude brighter than 6. Such
a system will provide a unique and ideal tool for the detection of young (<100 Myr) self-luminous planets and
hot debris disks in the immediate vicinity (0.1 to a few AUs) of nearby (< 50pc) stars.
Impact of calibration on extrasolar planets direct imaging with IRDIS, the infrared dual-imaging camera and spectrograph for SPHERE
Show abstract
The detection and characterization of extrasolar planets by direct imaging is becoming more and
more promising with the preparation of dedicated high-contrast instruments and the help of new data
analysis techniques. SPHERE (Spectro-Polarimetric High-contrast imager for Exoplanets REsearch)
is currently being developed as part of the second generation instruments of the ESO-VLT. IRDIS,
one of the SPHERE subsystems, will provide dual-band imaging with several filter pairs covering
the near-infrared from 0.95 to 2.3 microns, among with other observing modes such as long slit
spectroscopy and infrared polarimetry. This paper describes the instrument performances and the
impact of instrumental calibrations on finding and characterizing extrasolar planets, and on
observing strategies. It discusses constraints to achieve the required contrast of ~106 within few
hours of exposure time.
CARMENES: Calar Alto high-resolution search for M dwarfs with exo-earths with a near-infrared Echelle spectrograph
Show abstract
CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical
Echelle Spectrographs) is a next-generation instrument to be built for the 3.5m telescope at the Calar Alto
Observatory by a consortium of Spanish and German institutions. Conducting a five-year exoplanet survey
targeting ~ 300 M stars with the completed instrument is an integral part of the project. The CARMENES
instrument consists of two separate spectrographs covering the wavelength range from 0.52 to 1.7 μm at a spectral
resolution of R = 85, 000, fed by fibers from the Cassegrain focus of the telescope. The spectrographs are housed
in a temperature-stabilized environment in vacuum tanks, to enable a 1m/s radial velocity precision employing
a simultaneous ThAr calibration.
Ground-based Infrared Instruments I
The FIRE infrared spectrometer at Magellan: construction and commissioning
Show abstract
We describe the construction and commissioning of FIRE, a new 0.8-2.5μm echelle spectrometer for the Magellan/
Baade 6.5 meter telescope. FIRE delivers continuous spectra over its full bandpass with nominal spectral
resolution R = 6000. Additionally it offers a longslit mode dispersed by the prisms alone, covering the full z to
K bands at R ~ 350. FIRE was installed at Magellan in March 2010 and is now performing shared-risk science
observations. It is delivering sharp image quality and its throughput is sufficient to allow early observations of
high redshift quasars and faint brown dwarfs. This paper outlines several of the new or unique design choices
we employed in FIRE's construction, as well as early returns from its on-sky performance.
Recent progress on the KMOS multi-object integral-field spectrograph for ESO VLT
Show abstract
KMOS is a near-infrared multi-object integral-field spectrometer which is one of a suite of second-generation
instruments under construction for the VLT. The instrument is being built by a consortium of UK and German
institutes working in partnership with ESO and is now in the manufacture, integration and test phase. In this paper
we present an overview of recent progress with the design and build of KMOS and present the first results from the
subsystem test and integration.
GNOSIS: an OH suppression unit for near-infrared spectrographs
Show abstract
GNOSIS is an OH suppression unit to be used in conjunction with existing spectrographs. The OH suppression
is achieved using fibre Bragg gratings (FBGs), and will deliver the darkest near-infrared background of any
ground-based instrument. Laboratory and on-sky tests demonstrate that FBGs can suppress OH lines by 30dB
whilst maintaing > 90% throughput between the lines, resulting in a 4 mag decrease in the background.
In the first implementation GNOSIS will feed IRIS2 on the AAT. It will consist of a seven element lenslet
array, covering 1.4" on the sky, and will suppress the 103 brightest OH lines between 1.47 and 1.70 μm. Future
upgrades will include J-band suppression and implementation on an 8m telescope.
Spectropolarimetry with the SALT RSS
Show abstract
The large (~10 m) aperture of the Southern African Large Telescope (SALT) coupled with the unique capabilities
of the Robert Stobie Spectrograph (RSS), promises unparalleled prospects for polarimetric observations on an
8 - 10 m class telescope. RSS is a highly versatile first-generation instrument of the SALT. Results from
some of the first commissioning observations with the RSS are presented. A method for reducing SALT RSS
spectropolarimetry data is proposed and verified on observations of unpolarised and polarised standard stars. The
results provide estimates of telescope and instrumental polarisation as well as a calibration of the instrument's
polarimetric position angle offset.
ARCHONS: a highly multiplexed superconducting optical to near-IR camera
Show abstract
We report on the development of ARCONS, the ARray Camera for Optical to Near-IR Spectrophotometry.
This photon counting integral field unit (IFU), being built at UCSB and Caltech with detectors fabricated at
JPL, will use a unique, highly multiplexed low temperature detector technology known as Microwave Kinetic
Inductance Detectors (MKIDs). These detectors, which operate at 100 mK, should provide photon counting
with energy resolution of R = E/δE > 20 and time resolution of a microsecond, with a quantum efficiency of
around 50%. We expect to field the instrument at the Palomar 200" telescope in the first quarter of 2011 with
an array containing 1024 pixels in a 32×32 pixel form factor to yield a field of view of approximately 10×10
arcseconds. The bandwidth of the camera is limited by the rising sky count rate at longer wavelengths, but
we anticipate a bandwidth of 0.35 to 1.35 μm will be achievable. A simple optical path and compact dewar
utilizing a cryogen-free adiabatic demagnetization refridgerator (ADR) allows the camera to be deployed quickly
at Naysmith or Coud´e foci at a variety of telescopes. A highly expandable software defined radio (SDR) readout
that can scale up to much larger arrays has been developed.
NESSI: the New Mexico Tech Extrasolar Spectroscopic Survey Instrument
Show abstract
Less than 20 years after the discovery of the first extrasolar planet, exoplanetology is rapidly growing with more than
one discovery every week on average since 2007. An important step in exoplanetology is the chemical characterization
of exoplanet atmospheres. It has recently been shown that molecular signatures of transiting exoplanets can be studied
from the ground. To advance this idea and prepare more ambitious missions such as THESIS, a dedicated spectrometer
named the New Mexico Tech Extrasolar Spectroscopic Survey Instrument (NESSI) is being built at New Mexico Tech
in collaboration with the NASA Jet Propulsion Laboratory. NESSI is a purpose-built multi-object spectrograph that
operates in the J, H, and K-bands with a resolution of R = 1000 in each, as well as a lower resolution of R = 250 across
the entire J/H/K region.
Commissioning of the infrared imaging survey (IRIS) system
Show abstract
The Infrared Imaging System (IRIS) is a 0.8m telescope and a 1024×1024 pixels camera (IRISCAM) with a HAWAII-1
detector array. IRIS is located at the Cerro Armazones Observatory in Chile that is operated by the Ruhr University
Bochum jointly with the Universidad Católica del Norte in Antofagasta. It will be used primarily to survey star-forming
regions for variability. Our goal is to discover young stellar objects undergoing accretion instabilities or rotational
modulation of star spots, eclipsing binaries, and variable reflection nebulae. The telescope and the infrared camera are
completed and first light was achieved in May of 2010. IRIS is currently being tested and characterized, before the longterm
monitoring project will commence.
Development of the mid-IR echelle high-dispersion spectrograph employing the germanium immersion grating
Yasuhiro Hirahara,
Tsuyoshi Hirao,
Yoshio Tatamitani,
et al.
Show abstract
We have developed a germanium immersion grating mid-infrared cryogenic spectrograph (GIGMICS) designed for the
Nasmyth focus stage of NAOJ Subaru 8.2 m telescope, which operates at N-band (8-13 μm) in wavelength with the R ~
50,000. A single crystal germanium immersion echelle grating (30 × 30 × 72 mm) for collimated beam size of Φ28 mm
was fabricated by utilizing ultra precision micro-grinding method coupled with the ELID (ELectrolytic In-process
Dressing) technique (Ohmori, H. 1992)1. All optical components are arranged on the 800 mm diameter cold optical base
plate (~30 K) of the cryostat. By the Si:As IBC (Impurity Band Conductor) focal plane array (FPA) detector (412 × 512
pixels, unit pixel size 30 μm) operated at 5 K simultaneously acquires ~13 % wavelength coverage for N-band. The
instrument has been assembled and is now tested for the application to the gas-phase IR high-resolution spectroscopy.
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph
Show abstract
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) will use a dedicated 300-fiber, narrow-band
(1.5-1.7 micron), high resolution (R~30,000), near-infrared spectrograph to survey approximately 100,000 giant stars
across the Milky Way. This survey, conducted as part of the Sloan Digital Sky Survey III (SDSS III), will revolutionize
our understanding of kinematical and chemical enrichment histories of all Galactic stellar populations. The instrument,
currently in fabrication, will be housed in a separate building adjacent to the 2.5 m SDSS telescope and fed light via
approximately 45-meter fiber runs from the telescope. The instrument design includes numerous technological
challenges and innovations including a gang connector that allows simultaneous connection of all fibers with a single
plug to a telescope cartridge that positions the fibers on the sky, numerous places in the fiber train in which focal ratio
degradation must be minimized, a large (290 mm x 475 mm elliptically-shaped recorded area) mosaic-VPH, an f/1.4 sixelement
refractive camera featuring silicon and fused silica elements with diameters as large as 393 mm, three near-within a custom, LN2-cooled, stainless steel vacuum cryostat with dimensions 1.4 m x 2.3 m x 1.3 m.
Ground-based Infrared Instruments II
Design and development of MOSFIRE: the multi-object spectrometer for infrared exploration at the Keck Observatory
Show abstract
MOSFIRE is a unique multi-object spectrometer and imager for the Cassegrain focus of the 10 m Keck 1 telescope. A
refractive optical design provides near-IR (0.97 to 2.45 μm) multi-object spectroscopy over a 6.14' x 6.14' field of view
with a resolving power of R~3,270 for a 0.7" slit width (2.9 pixels in the dispersion direction), or imaging over a field of
view of 6.8' diameter with 0.18" per pixel sampling. A single diffraction grating can be set at two fixed angles, and
order-sorting filters provide spectra that cover the K, H, J or Y bands by selecting 3rd, 4th, 5th or 6th order respectively. A
folding flat following the field lens is equipped with piezo transducers to provide tip/tilt control for flexure compensation
at the 0.1 pixel level. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is achieved using a
cryogenic Configurable Slit Unit or CSU developed in collaboration with the Swiss Centre for Electronics and Micro
Technology (CSEM). The CSU is reconfigurable under remote control in less than 5 minutes without any thermal
cycling of the instrument. Slits are formed by moving opposable bars from both sides of the focal plane. An individual
slit has a length of 7.1" but bar positions can be aligned to make longer slits. When masking bars are removed to their
full extent and the grating is changed to a mirror, MOSFIRE becomes a wide-field imager. Using a single, ASIC-driven,
2K x 2K H2-RG HgCdTe array from Teledyne Imaging Sensors with exceptionally low dark current and low noise,
MOSFIRE will be extremely sensitive and ideal for a wide range of science applications. This paper describes the design
and testing of the instrument prior to delivery later in 2010.
OCTOCAM: a fast multichannel imager and spectrograph for the 10.4m GTC
Show abstract
OCTOCAM is a multi-channel imager and spectrograph that has been proposed for the 10.4m GTC telescope. It will use
dichroics to split the incoming light to produce simultaneous observations in 8 different bands, ranging from the
ultraviolet to the near-infrared. The imaging mode will have a field of view of 2' x 2' in u, g, r, i, z, J, H and KS bands,
whereas the long-slit spectroscopic mode will cover the complete range from 4,000 to 23,000 A with a resolution of 700
- 1,000 (depending on the arm and slit width). An additional mode, using an image slicer, will deliver a spectral
resolution of over 3,000. As a further feature, it will use state of the art detectors to reach high readout speeds of the
order of tens of milliseconds. In this way, OCTOCAM will be occupying a region of the time resolution - spectral
resolution - spectral coverage diagram that is not covered by a single instrument in any other observatory, with an
exceptional sensitivity.
First end-end performance testing and results for KMOS
Philip Rees,
Michele Cirasuolo,
Ian J. Lewis,
et al.
Show abstract
KMOS is a modular design consisting of three identical parallel segments which in turn contain eight integral field
channels. The assembly and integration plan is to build up the instrument step by step and test performance at each stage.
The first end to end chain was complete at the end of 2009 and testing commenced. This paper describes the philosophy
and management of the test programme, the testing procedures used to study the instrument performance as the light path
was built and the results obtained.
EAGLE ISS: a modular twin-channel integral-field near-IR spectrograph
Show abstract
The ISS (Integral-field Spectrograph System) has been designed as part of the EAGLE Phase A Instrument Study for the
E-ELT. It consists of two input channels of 1.65x1.65 arcsec field-of-view, each reconfigured spatially by an imageslicing
integral-field unit to feed a single near-IR spectrograph using cryogenic volume-phase-holographic gratings to
disperse the image spectrally. A 4k x 4k array detector array records the dispersed images. The optical design employs
anamorphic magnification, image slicing, VPH gratings scanned with a novel cryo-mechanism and a three-lens camera.
The mechanical implementation features IFU optics in Zerodur, a modular bench structure and a number of highprecision
cryo-mechanisms.
Performances of X-shooter, the new wide-band intermediate resolution spectrograph at the VLT
Show abstract
X-shooter is the first second-generation instrument newly commissioned a the VLT. It is a high efficiency single
target intermediate resolution spectrograph covering the range 300 - 2500 nm in a single shot. We summarize
the main characteristics of the instrument and present its performances as measured during commissioning and
the first months of science operations.
Commissioning the VISTA IR camera
Show abstract
VISTA was designed as a survey facility, and was optimized for use with the 64Mpix VISTA IR Camera in the sense
that the optical system of the instrument and telescope was designed as a single entity. The commissioning of the IR
camera therefore formed a major part of the system integration and commissioning of the whole VISTA system. We
describe some aspects of the commissioning process for VISTA, the interplay between the camera and telescope
systems, and summarize the results of the verification phase.
FMOS the fibre multiple-object spectrograph, part VIII: current performances and results of the engineering observations
Show abstract
The Fibre Multi-Object Spectrograph for Subaru Telescope (FMOS) is a near-infrared instrument with 400
fibres in a 30' filed of view at F/2 prime focus. To observe 400 objects simultaneously, we have developed a fibre
positioner called "Echidna" using a tube piezo actuator. We have also developed two OH-airglow suppressed and
refrigerated spectrographs. Each spectrograph has two spectral resolution modes: the low-resolution mode and
the high-resolution mode. The low-resolution mode covers the complete wavelength range of 0.9 - 1.8 μm with
one exposure, while the high-resolution mode requires four exposures at different camera positions to cover the
full wavelength range. The first light was accomplished in May 2008. The science observations and the open-use
observations begin in May 2010.
LUCIFER1 commissioning at the LBT
Show abstract
LUCIFER 1 is the rst of two identical camera-spectrograph units installed at the LBT (Large Binocular Telescope)
on Mount Graham in Arizona. Its commissioning took place between September 2008 and November
2009 and has immediately been followed by science operations since December 2009.
LUCIFER has a 4x4 arcminute eld of view. It is equipped with a 2048x2048 pixel HAWAII-2 array, suitable
lters (broad-band z, J, H, K & Ks plus 12 medium and narrow band near-infrared lters) and three gratings for
spectroscopy for a resolution of up to 15000. LUCIFER has 3 cameras: two specic for seeing limited imaging
(the N3.75 camera, with 0.12"/pixel) and spectroscopy (the N1.8 camera, with 0.25"/pixel) and one for diraction
limited observations (the N30 camera). We report here about the completed seeing-limited commissioning, thus
using only two of the cameras.
Preliminary design of IGRINS (Immersion GRating INfrared Spectrograph)
Show abstract
The Korea Astronomy and Space Science Institute (KASI) and the Department of Astronomy at the University of Texas
at Austin (UT) are developing a near infrared wide-band high resolution spectrograph, IGRINS. IGRINS can observe all
of the H- and K-band atmospheric windows with a resolving power of 40,000 in a single exposure. The spectrograph
uses a white pupil cross-dispersed layout and includes a dichroic to divide the light between separate H and K cameras,
each provided with a 2kx2k HgCdTe detector. A silicon immersion grating serves as the primary disperser and a pair of
volume phased holographic gratings serve as cross dispersers, allowing the high resolution echelle spectrograph to be
very compact. IGRINS is designed to be compatible with telescopes ranging in diameter from 2.7m (the Harlan J. Smith
telescope; HJST) to 4 - 8 m telescopes. Commissioning and initial operation will be on the 2.7m telescope at McDonald
Observatory from 2013.
Techniques and Components II
GPI: cryogenic spectrograph optics performances
Show abstract
The science instrument for GPI (Gemini Planet Imager) is a cryogenic integral field spectrograph
based on a lenslet array. The integral field nature of the instrument allows for a full mapping of the
focal plane at coarse spectral resolution. With such a data cube, artifacts within the PSF such as
residual speckles can be suppressed. Additionally, the initial detection of any candidate planet will
include spectral information that can be used to distinguish it from a background object: candidates
can be followed up with detailed spectroscopic observations. The optics between the lenslet array
and the detector are essentially a standard spectrograph with a collimating set of lenses, a dispersive
prism and a camera set of lenses in a folded assembly. We generally refer to this optical set as the
spectrograph optics. This paper describes the laboratory optical performances over the field of view.
The test procedure includes the imaging performances in both non dispersive and dispersive mode.
The test support equipments include a test cryostat, an illumination module with monochromatic
fiber laser, a wideband light source and a test detector module.
Sparse aperture masking (SAM) at NAOS/CONICA on the VLT
Show abstract
The new operational mode of aperture masking interferometry has been added to the CONICA camera which
lies downstream of the Adaptive Optics (AO) corrected focus provided by NAOS on the VLT-UT4 telescope.
Masking has been shown to deliver superior PSF calibration, rejection of atmospheric noise and robust recovery
of phase information through the use of closure phases. Over the resolution range from about half to several
resolution elements, masking interferometry is presently unsurpassed in delivering high fidelity imaging and
direct detection of faint companions. Here we present results from commissioning data using this powerful new
operational mode, and discuss the utility for masking in a variety of scientific contexts. Of particular interest is
the combination of the CONICA polarimetry capabilities together with SAM mode operation, which has revealed
structures never seen before in the immediate circumstellar environments of dusty evolved stars.
The first VisAO-fed integral field spectrograph: VisAO IFS
Show abstract
We present the optomechanical design of the Magellan VisAO Integral Field Spectrograph (VisAO IFS),
designed to take advantage of Magellan's AO system and its 85.1cm concave ellipsoidal Adaptive Secondary Mirror
(ASM). With 585 actuators and an equal number of actively-controlled modes, this revolutionary second generation
ASM will be the first to achieve moderate Strehl ratios into the visible wavelength regime. We have designed the VisAO
IFS to be coupled to either Magellan's LDSS-3 spectrograph or to the planned facility M2FS fiber spectrograph and to
optimize VisAO science. Designed for narrow field-of-view, high spatial resolution science, this lenslet-coupled fiberfed
IFS will offer exciting opportunities for scientific advancement in a variety of fields, including protoplanetary disk
morphology and chemistry, resolution and spectral classification of tight astrometric binaries, seasonal changes in the
upper atmosphere of Titan, and a better understanding of the black hole M-sigma relation.
XMS and NG1dF: extreme multiplex spectrographs for wide-field multi-object spectroscopy
Show abstract
Two feasibility studies for spectrographs that can deliver at least 4000 MOS slits over a 1° field at the prime focuses of
the Anglo-Australian and Calar Alto Observatories have been completed. We describe the design and science case of the
Calar Alto eXtreme Multiplex Spectrograph (XMS) for which an extended study, half way between feasibility study and
phase-A, was made. The optical design is quite similar than in the AAO study for the Next Generation 1 degree Field
(NG1dF) but the mechanical design of XMS is quite different and much more developed. In a single night, 25000 galaxy
redshifts can be measured to z~0.7 and beyond for measuring the Baryon Acoustic Oscillation (BAO) scale and many
other science goals. This may provide a low-cost alternative to WFMOS for example and other large fibre spectrographs.
The design features four cloned spectrographs which gives a smaller total weight and length than a unique spectrograph
to makes it placable at prime focus. The clones use a transparent design including a grism in which all optics are about
the size or smaller than the clone rectangular subfield so that they can be tightly packed with little gaps between
subfields. Only low cost glasses are used; the variations in chromatic aberrations between bands are compensated by
changing a box containing the grism and two adjacent lenses. Three bands cover the 420nm to 920nm wavelength range
at 10A resolution while another cover the Calcium triplet at 3A. An optional box does imaging. We however also studied
different innovative methods for acquisition without imaging. A special mask changing mechanism was also designed to
compensate for the lack of space around the focal plane. Conceptual designs for larger projects (AAT 2º field, CFHT,
VISTA) have also been done.
Focal plane detectors for Dark Energy Camera (DECam)
Show abstract
The Dark Energy Camera is an wide field imager currently
under construction for the Dark Energy Survey.
This instrument will use fully depleted 250 μm thick
CCD detectors selected for their higher quantum efficiency
in the near infrared with respect to thinner devices.
The detectors were developed by LBNL using
high resistivity Si substrate. The full set of scientific
detectors needed for DECam has now been fabricated,
packaged and tested. We present here the results of
the testing and characterization for these devices and
compare these results with the technical requirements
for the Dark Energy Survey.
On-sky demonstration of optical speckle stabilization using the SPIFS-POC
Show abstract
We present on-sky performance results of a new technique, speckle stabilization, with the Stabilized sPeckle
Integral Field Spectrograph Proof-Of-Concept (SPIFS-POC) instrument. The SPIFS-POC is an optical-imaging
instrument capable of high spatial resolutions much finer than the seeing-limit. It achieves this aim by measuring
speckle patterns in real time (through the use of an L3CCD), finding the highest quality speckle, and stabilizing
it onto a traditional, low readout speed science camera through the use of a fast steering mirror. This process
is repeated at ≈100 Hz over the course of long exposures resulting in a high-resolution core surrounded by a
diffuse halo. We show that in the Sloan z' bands, SPIFS is able to acquire spatial resolutions much greater than
the seeing limit, even approaching 3λ/D. We also discuss improvements for the next phase of the SPIFS project
where we fully expect to be able to recover diffraction-limited spatial resolutions in the optical.
Airborne instrumentation
FIFI LS getting ready to fly aboard SOFIA
Show abstract
FIFI LS is the German far-infrared integral field spectrometer for the SOFIA airborne observatory. The instrument consists
of two independent integral field spectrometers for two different wavelength bands (45-110 μm and 100-200 μm). A
dichroic filter enables simultaneous observation of two different spectral lines in the same field-of view. This allows very
efficient mapping of extended regions with FIFI LS in many important far-infrared cooling lines with line ratios sensitive to
temperature and density.
FIFI LS will become a facility instrument for SOFIA. In the next two years it will become a fully commissioned facility
instrument. After its commission, FIFI LS will be available for general observing with a large science potential. In this
paper, we will also discuss the science of FIFI LS.
FORCAST: a first light facility instrument for SOFIA
Show abstract
FORCAST is the "first light" U. S. science instrument to fly aboard SOFIA. FORCAST offers dual channel imaging in
discrete filters at 5 - 25 microns and 30 - 40 microns, with diffraction-limited imaging at wavelengths > 15 microns.
FORCAST has a plate scale of 0.75 arcsec per pixel, giving it a 3.2 arcmin x 3.2 arcmin FOV on SOFIA. We give a
status update on FORCAST development, including the performance of new far-IR filters; design and performance of
the calibration box; laboratory operations and performance; and results from ground-based and first flight operations.
CASIMIR: a high resolution far-IR/submm spectrometer for airborne astronomy
Show abstract
CASIMIR, the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver, is a far-infrared
and submillimeter heterodyne spectrometer, being developed for the Stratospheric Observatory For Infrared Astronomy,
SOFIA. CASIMIR will use newly developed superconducting-insulating-superconducting (SIS) mixers.
Combined with the 2.5 m mirror of SOFIA, these detectors will allow observations with high sensitivity to be
made in the frequency range from 500 GHz up to 1.4 THz. Initially, at least 5 frequency bands in this range
are planned, each with a 4-8 GHz IF passband. Up to 4 frequency bands will be available on each flight and
bands may be swapped readily between flights. The local oscillators for all bands are synthesized and tuner-less,
using solid state multipliers. CASIMIR also uses a novel, commercial, field-programmable gate array (FPGA)
based, fast Fourier transform spectrometer, with extremely high resolution, 22000 (268 kHz at 6 GHz), yielding
a system resolution > 106. CASIMIR is extremely well suited to observe the warm, ≈ 100K, interstellar medium,
particularly hydrides and water lines, in both galactic and extragalactic sources. We present an overview of the
instrument, its capabilities and systems. We also describe recent progress in development of the local oscillators
and present our first astronomical observations obtained with the new type of spectrometer.
The cosmic infrared background experiment (CIBER): instrumentation and first results
M. Zemcov,
J. Battle,
J. Bock,
et al.
Show abstract
Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a
process which was completed by z ~ 6; the wavelength of these photons has been redshifted by (1 + z) into
the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First
flying in February 2009, the Cosmic Infrared Background ExpeRiment (CIBER) comprises four instruments
housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the
extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband
imaging instruments, make a detailed characterization of the spectral shape of the IR background using a
low resolution spectrometer, and measure the absolute brightness of the Zodiacal light foreground with a high
resolution spectrometer in each of our six science fields. The scientific motivation for CIBER and details of its
first and second flight instrumentation will be discussed. First flight results on the color of the zodiacal light
around 1 μm and plans for the future will also be presented.
Solar Instrumentation
Feasibility study of high-resolution integral-field spectrographs for EST with multislit and multi-wavelength capabilities
Show abstract
This communication shows the feasibility study of a new instrument designed for the 4 meter European Solar Telescope
(EST) for high resolution spectro-polarimetric observations. This paper is specifically focused on the spectrographs that
allow the simultaneous observation of 5 visible and 4 near-infrared wavelengths (complying with the science
requirements), with 8 entrance slits of 200arcsec each fed by an integral field unit covering an area on the solar surface
of 9 x 9 arcsec2.
ZIMPOL-3: a powerful solar polarimeter
Renzo Ramelli,
Silvano Balemi,
Michele Bianda,
et al.
Show abstract
The area of high precision solar spectropolarimetry has made great advances in recent years and the Zurich
IMaging POLarimeter (ZIMPOL) systems have played a major role in that. ZIMPOL reaches a polarimetric
accuracy of 10-5 by using fast (kHz) polarization modulation/demodulation of the light beam in combination
with large-area array detectors. A new generation of improved cameras (ZIMPOL-3) are being implemented for
the scientific observations at the solar observatory at Istituto Ricerche Solari Locarno. The new system is based
on a flexible and compact modular design, which easily adapts to new applications. A faster electronics and new
sensors with higher quantum efficency compared to the previous ZIMPOL versions, allow to achieve a better
overall efficency. Future plans include observing campaigns at foremost large telescopes and the exploration of
new technologies (e.g. CMOS).
Auxiliary full-disc telescope for the European Solar Telescope
Michal Sobotka,
Miroslav Klvaña,
Zbynék Melich,
et al.
Show abstract
The Auxiliary Full-Disc Telescope (AFDT) will be used for the orientation of the observer on the solar disc
and in its surroundings, for an easy guidance of the European Solar Telescope (EST) to a selected target,
and for precise coordinate measurements. AFDT can be used as an autonomous robotic telescope for synoptic
observations and records of solar activity also when no observations are carried out at the EST main telescope.
The principal functions of AFDT and the related requirements are summarised. The specific axial mechanical
structure accommodating the refractor optical system is outlined. The optical system and its components are
described. Two alternatives of the positional control system - the active guiding system and the passive guiding
system - are described and their functionality is analysed.
Spectrograph capabilities of the European Solar Telescope
Show abstract
EST is a project for a 4-meter class telescope to be located in the Canary Islands. EST will be optimized for studies of
the magnetic coupling between the photosphere and the chromosphere. This requires high spatial and temporal resolution
diagnostics tools of properties of the plasma, by using multiple wavelength spectropolarimetry. To achieve these goals,
visible and near-IR multi-purpose spectrographs are being designed to be compatible with different modes of use: LsSS
(Long-slit Standard Spectrograph), multi-slit multi-wavelength spectrograph with an integral field unit, TUNIS (Tunable
Universal Narrow-band Imaging Spectrograph), and new generation MSDP (Multi-channel Subtractive Double-pass
Spectrograph). In this contribution, these different instrumental configurations are described.
The ATST visible broadband imager: a case study for real-time image reconstruction and optimal data handling
Show abstract
At future telescopes, adaptive optics systems will play a role beyond the correction of Earth's atmosphere.
These systems are capable of delivering information that is useful for instrumentation, e.g. if reconstruction
algorithms are employed to increase the spatial resolution of the scientific data. For the 4m aperture Advanced
Technology Solar Telescope (ATST), a new generation of state-of-the-art instrumentation is developed that will
deliver observations of the solar surface at unsurpassed high spatial resolution. The planned Visual Broadband
Imager (VBI) is one of those instruments. It will be able to record images at an extremely high rate and compute
reconstructed images close to the telescope's theoretical diffraction limit using a speckle interferometry algorithm
in near real-time. This algorithm has been refined to take data delivered by the adaptive optics system into
account during reconstruction. The acquisition and reconstruction process requires the use of a high-speed data
handling infrastructure to retrieve the necessary data from both adaptive optics system and instrument cameras.
We present the current design of this infrastructure for the ATST together with a feasibility analysis of the
underlying algorithms.
Instrumentation for ELTs I
The TMT instrumentation program
Show abstract
An overview of the current status of the Thirty Meter Telescope (TMT) instrumentation program is presented.
Conceptual designs for the three first light instruments (IRIS, WFOS and IRMS) are in progress, as well as feasibility
studies of MIRES. Considerable effort is underway to understand the end-to-end performance of the complete telescopeadaptive
optics-instrument system under realistic conditions on Mauna Kea. Highly efficient operation is being designed
into the TMT system, based on a detailed investigation of the observation workflow to ensure very fast target acquisition
and set up of all subsystems. Future TMT instruments will almost certainly involve contributions from institutions in
many different locations in North America and partner nations. Coordinating and optimizing the design and construction
of the instruments to ensure delivery of the best possible scientific capabilities is an interesting challenge. TMT
welcomes involvement from all interested instrument teams.
An overview of the E-ELT instrumentation programme
Show abstract
In this paper we present a brief status report on the conceptual designs of the instruments and adaptive optics modules
that have been studied for the European Extremely Large Telescope (E-ELT). In parallel with the design study for the
42-m telescope, ESO launched 8 studies devoted to the proposed instruments and 2 for post-focal adaptive optics
systems. The studies were carried out in consortia of ESO member state institutes or, in two cases, by ESO in
collaboration with external institutes. All studies have now been successfully completed. The result is a powerful set of
facility instruments which promise to deliver the scientific goals of the telescope.
The aims of the individual studies were broad: to explore the scientific capabilities required to meet the E-ELT science
goals, to examine the technical feasibility of the instrument, to understand the requirements placed on the telescope
design and to develop a delivery plan. From the perspective of the observatory, these are key inputs to the development
of the proposal for the first generation E-ELT instrument suite along with the highest priority science goals and
budgetary and technical constraints. We discuss the lessons learned and some of the key results of the process.
Science instrument development for the Giant Magellan Telescope
Show abstract
The Giant Magellan Telescope (GMT) is a 24.5m diameter optical/infrared telescope. Its seven 8.4m primary mirrors
give it a collecting area equivalent to a 21.4m filled aperture. The ten GMT partners are constructing the telescope at the
Las Campanas Observatory in Chile with first light planned for the end of 2018. In this paper, we describe the plans for
the first-generation focal plane instrumentation for the telescope. The GMTO Corporation has solicited studies for
instruments capable of carrying out the broad range of objectives outlined in the GMT Science Case. Six instruments
have been selected for 14 month long conceptual design studies. We briefly describe the features of these instruments
and give examples of the major science questions that they can address.
Pixel-One
Show abstract
The early future of astronomy will be dominated by Extremely Large Telescopes where the focal
lengths will be of the order of several hundred meters. This yields focal plane sizes of roughly one
square meter to obtain a field of view of about 5 x 5 arcmin. When operated in seeing limited mode this
field is correctly sampled with 1x1mm pixels. Such a sampling can be achieved using a peculiar array
of tiny CMOS active photodiodes illuminated through microlenses or lightpipes. If the photodiode is
small enough and utilizes the actual pixel technology, its dark current can be kept well below the sky
background photocurrent, thus avoiding the use of cumbersome cryogenics systems. An active smart
electronics will manage each pixel up to the A/D conversion and data transfer. This modular block is
the Pixel-One. A 30x30 mm tile filled with 1000 Pixel-Ones could be the basic unit to mosaic very
large focal planes. By inserting dispersion elements inside the optical path of the lenslet array one
could also produce a low dispersed spectrum of each focal plane sub-aperture and, by using an array of
few smart photodiodes, also get multi-wavelength information in the optical band for each equivalent
focal plane pixel. An application to the E-ELT is proposed.
Progress of the conceptual design for the MOBIE imaging spectrograph for the Thirty Meter Telescope
Show abstract
The Multi-Object Broadband Imaging Echellette (MOBIE) is the seeing-limited, wide-field multi-object optical imaging
spectrograph planned for first-light operation on the Thirty Meter Telescope (TMT). Following the completion of a
feasibility study and requirements review in December 2008, the MOBIE instrument project, based at the University of
California Observatories (UCO) on the UC Santa Cruz campus, entered a conceptual design phase. In this paper, we
describe the latest developments in the instrument optical design, and progress in the conceptual design of the optomechanical
and mechanical elements for the instrument.
DIORAMAS: a wide-field visible and near-infrared imaging multi-slit spectrograph for the EELT
Olivier Le Fèvre,
Dario Maccagni,
Stéphane Paltani,
et al.
Show abstract
We present the science, design and performances of DIORAMAS, an imager and multi-slit spectrograph for the
European Extremely Large Telescope. It covers a wide 6.8x6.8 arcmin2 field, a large wavelength range 0.37 to 1.6
microns. The exceptional performances of this concept will enable extremely deep images to magnitudes AB~30 and
high multiplex spectroscopy with up to ~500 slits observed simultaneously at spectral resolutions from R~300 to more
than 120 slits at R~3000. The technical design is robust with only proven technology, and DIORAMAS could be
developed on a timescale compatible with the EELT first light.
The infrared imaging spectrograph (IRIS) for TMT: instrument overview
Show abstract
We present an overview of the design of IRIS, an infrared (0.85 - 2.5 micron) integral field spectrograph and imaging
camera for the Thirty Meter Telescope (TMT). With extremely low wavefront error (<30 nm) and on-board wavefront
sensors, IRIS will take advantage of the high angular resolution of the narrow field infrared adaptive optics system
(NFIRAOS) to dissect the sky at the diffraction limit of the 30-meter aperture. With a primary spectral resolution of
4000 and spatial sampling starting at 4 milliarcseconds, the instrument will create an unparalleled ability to explore high
redshift galaxies, the Galactic center, star forming regions and virtually any astrophysical object. This paper summarizes
the entire design and basic capabilities. Among the design innovations is the combination of lenslet and slicer integral
field units, new 4Kx4k detectors, extremely precise atmospheric dispersion correction, infrared wavefront sensors, and a
very large vacuum cryogenic system.
MICADO: the E-ELT adaptive optics imaging camera
Show abstract
MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted
to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (~1 arcmin) field
of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis
diffraction limited performance using natural guide stars. We discuss the instrument's key capabilities and
expected performance, and show how the science drivers have shaped its design. We outline the technical
concept, from the opto-mechanical design to operations and data processing. We describe the AO module,
summarise the instrument performance, and indicate some possible future developments.
Instrumentation for ELTs II
SIMPLE: a high-resolution near-infrared spectrometer for the E-ELT
Livia Origlia,
Ernesto Oliva,
Roberto Maiolino,
et al.
Show abstract
SIMPLE is an optimized near IR echelle spectrograph for the E-ELT assisted by adaptive optics. It delivers a complete
0.84-2.5μm spectrum in one exposure with resolution up to R=130,000, nearly diffraction limited pixel scale and
limiting magnitudes down to JHK~20. Its most prominent science cases include the study of the intergalactic medium in
the early Universe (z>6) and of the atmospheres of exo-planet transiting nearby low mass stars.
Design concepts for a mid-infrared instrument for the Thirty-Meter Telescope
Show abstract
A mid-infrared imager and spectrometer is under consideration for construction in the first decade of the Thirty-
Meter Telescope (TMT) operation (see the companion paper by Okamoto). MIRES, a mid-infrared high-spectral
resolution optimized instrument, was previously proposed to provide these capabilities to the TMT community.
We have revised the design in order to provide an improved optical design for the high-spectral resolution
mode with R=120,000, improved imaging with sky chopping, low-spectral resolution mode with an integral
field spectrograph, and polarimetry. In this paper we describe the optical design concepts currently under
consideration.
EAGLE: a MOAO fed multi-IFU NIR workhorse for E-ELT
Show abstract
EAGLE is an instrument under consideration for the European Extremely Large Telescope (E-ELT). EAGLE will be
installed at the Gravity Invariant Focal Station of the E-ELT. The baseline design consists of 20 IFUs deployable over a
patrol field of ~40 arcmin2. Each IFU has an individual field of view of ~ 1.65" x 1.65". While EAGLE can operate with
the Adaptive Optics correction delivered by the telescope, its full and unrivaled scientific power will be reached with the
added value of its embedded Multi-Object Adaptive Optics System (MOAO). EAGLE will be a unique and efficient
facility for spatially-resolved, spectroscopic surveys of high-redshift galaxies and resolved stellar populations. We detail
the three main science drivers that have been used to specify the top level science requirements. We then present the
baseline design of the instrument at the end of Phase A, and in particular its Adaptive Optics System. We show that the
instrument has a readiness level that allows us to proceed directly into phase B, and we indicate how the instrument
development is planned.
EPICS: direct imaging of exoplanets with the E-ELT
Show abstract
Presently, dedicated instruments at large telescopes (SPHERE for the VLT, GPI for Gemini) are about to discover and
explore self-luminous giant planets by direct imaging and spectroscopy. The next generation of 30m-40m ground-based
telescopes, the Extremely Large Telescopes (ELTs), have the potential to dramatically enlarge the discovery space
towards older giant planets seen in reflected light and ultimately even a small number of rocky planets. EPICS is a
proposed instrument for the European ELT, dedicated to the detection and characterization of Exoplanets by direct
imaging, spectroscopy and polarimetry. ESO completed a phase-A study for EPICS with a large European consortium
which - by simulations and demonstration experiments - investigated state-of-the-art diffraction and speckle suppression
techniques to deliver highest contrasts. The paper presents the instrument concept and analysis as well as its main
innovations and science capabilities. EPICS is capable of discovering hundreds of giant planets, and dozens of lower
mass planets down to the rocky planets domain.
CODEX
Show abstract
CODEX is the proposed ultra-stable optical high-resolution spectrograph for the E-ELT, which will use novel Laser
Comb calibration techniques and an innovative design to open a new era for precision spectroscopy. With its unique
combination of light-collecting power and precision, CODEX will make it possible to directly measure the acceleration
of the Universe by monitoring the cosmological redshift drift of spectroscopic features at cosmological distances.
CODEX will also allow the assembly of the first sizeable sample of earth-like planets in the habitable zones of their stars
with the radial velocity technique. CODEX will take this technique to the level of cm/sec radial velocity stability - a
factor of about 20 improvement compared to current instruments. These are two of the scientific results anticipated for
CODEX, which will be complemented by a wide range of spectacular science in stellar, galactic and extra-galactic
Astronomy as well as Fundamental Physics. All the critical technology items are available or (as for the Laser Frequency
Comb) are in an advanced state of testing. CODEX is located at the E-ELT coudé focus that will cover the visible range
from 370 to 710 nm and provide a resolving power R~120000 with an aperture of 0.8 arcseconds in the sky.
Instrument concept and science case for the mid-IR E-ELT imager and spectrograph METIS
Show abstract
METIS is the 'Mid-infrared ELT Imager and Spectrograph', the only planned thermal/mid-IR instrument for the E-ELT.
METIS will provide diffraction limited imaging in the atmospheric L/M and N-band from 3 - 14 μm over an 18"×18"
field of view (FOV). The imager also includes high contrast coronagraphy and low-resolution (900 ≤ R ≤ 5000) long slit
spectroscopy and polarimetry. In addition, an IFU fed, high resolution spectrograph at L/M band will provide a spectral
resolution of R ~ 100,000 over a 0.4"×1.5" FOV. The adaptive optics (AO) system is relatively simple, and METIS can
reach its full performance with the adaptive correction provided by the telescope - and occasionally even under seeing
limited conditions. On a 42m ELT, METIS will provide state-of-the-art mid-IR performance from the ground. The
science case for METIS is based on proto-planetary disks, characterization of exoplanets, formation of our Solar System,
growth of supermassive black holes, and the dynamics of high-z galaxies. With the focus on highest angular resolution
and highest spectral resolution, METIS is highly complementary to JWST and ALMA. This paper summarizes the
science case for METIS, and describes the instrument concept, performance and operational aspects.
Instrumentation for ELTs III
The infrared imaging spectrograph (IRIS) for TMT: spectrograph design
Show abstract
The Infra-Red Imaging Spectrograph (IRIS) is one of the three first light instruments for the Thirty Meter Telescope
(TMT) and is the only one to directly sample the diffraction limit. The instrument consists of a parallel imager and offaxis
Integral Field Spectrograph (IFS) for optimum use of the near infrared (0.84um-2.4um) Adaptive Optics corrected
focal surface. We present an overview of the IRIS spectrograph that is designed to probe a range of scientific targets
from the dynamics and morphology of high-z galaxies to studying the atmospheres and surfaces of solar system objects,
the latter requiring a narrow field and high Strehl performance. The IRIS spectrograph is a hybrid system consisting of
two state of the art IFS technologies providing four plate scales (4mas, 9mas, 25mas, 50mas spaxel sizes). We present
the design of the unique hybrid system that combines the power of a lenslet spectrograph and image slicer spectrograph
in a configuration where major hardware is shared. The result is a powerful yet economical solution to what would
otherwise require two separate 30m-class instruments.
HARMONI: a single-field wide-band integral-field spectrograph for the European ELT
Show abstract
We describe the results of a Phase A study for a single field, wide band, near-infrared integral field spectrograph for the
European Extremely Large Telescope (E-ELT). HARMONI, the High Angular Resolution Monolithic Optical & Nearinfrared
Integral field spectrograph, provides the E-ELT's core spectroscopic requirement. It is a work-horse instrument,
with four different spatial scales, ranging from seeing to diffraction-limited, and spectral resolving powers of 4000,
10000 & 20000 covering the 0.47 to 2.45 μm wavelength range. It is optimally suited to carry out a wide range of
observing programs, focusing on detailed, spatially resolved studies of extended objects to unravel their morphology,
kinematics and chemical composition, whilst also enabling ultra-sensitive observations of point sources.
We present a synopsis of the key science cases motivating the instrument, the top level specifications, a description of
the opto-mechanical concept, operation and calibration plan, and image quality and throughput budgets. Issues of
expected performance, complementarity and synergies, as well as simulated observations are presented elsewhere in
these proceedings[1].
METIS opto-mechanical design and packaging study
Show abstract
METIS: "Mid-infrared ELT Imager and Spectrograph" is the mid-infrared (3 - 14 microns) instrument for imaging and
spectroscopy for the European Extremely Large Telescope (E-ELT). To ensure high detection sensitivity the internal
radiation of the instrument needs to be eliminated (sufficiently reduced) and thus needs to be operated at cryogenic
temperatures.
The instrument is divided in a cold and warm system. The cold system, the actual heart of the system, is subdivided into
five main opto-mechanical modules located within a common cryostat (part of the warm system). The warm system
provides the crucial environment for the cold system, including the instrument control and maintenance equipment. The
end 2009 finished Phase-A study carried out within the framework of the ESO sponsored E-ELT instrumentation studies
has been performed by an international consortium with institutes from Netherlands (PI: Bernhard Brandl - NOVA),
Germany, France, United Kingdom and Belgium. During this conference various aspects of the METIS instrument
(design) are presented in several papers, including the instrument concept and science case, and the system engineering
and optical design.
This paper describes the design constraints and key issues regarding the packaging of this complex cryogenic instrument.
The design solutions to create a light, small and fully accessible instrument are discussed together with the specific
subdivision of the cold and warm system to ensure concurrent development at various different institutes around Europe.
In addition the paper addresses the design and development studies for the special, challenging units such as the large
optical image de-rotator, the (2D) chopper mechanism and the special cryogenic drives.
GMTNIRS (Giant Magellan Telescope near-infrared spectrograph): design concept
Show abstract
We are designing a sensitive high resolution (R=60,000-100,000) spectrograph for the Giant Magellan Telescope
(GMTNIRS, the GMT Near-Infrared Spectrograph). Using large-format IR arrays and silicon immersion gratings, this
instrument will cover all of the J (longer than 1.1 μm), H, and K atmospheric windows or all of the L and M windows in
a single exposure. GMTNIRS makes use of the GMT adaptive optics system for all bands. The small slits will offer the
possibility of spatially resolved spectroscopy as well as superior sensitivity and wavelength coverage. The GMTNIRS
team is composed of scientists and engineers at the University of Texas, the Korea Astronomy and Space Science
Institute, and Kyung Hee University. In this paper, we describe the optical and mechanical design of the instrument. The
principal innovative feature of the design is the use of silicon immersion gratings which are now being produced by our
team with sufficient quality to permit designs with high resolving power and broad instantaneous wavelength coverage
across the near-IR.
Project overview of OPTIMOS-EVE: the fibre-fed multi-object spectrograph for the E-ELT
Show abstract
OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fibre fed multi object
spectrograph proposed for the European Extremely Large Telescope (E-ELT), planned to be operational in 2018 at Cerro
Armazones (Chile). It is designed to provide a spectral resolution of 6000, 18000 or 30000, at wavelengths from 370 nm
to 1.7 μm, combined with a high multiplex (>200) and a large spectral coverage. Additionally medium and large IFUs
are available. The system consists of three main modules: a fibre positioning system, fibres and a spectrograph.
The recently finished OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT
instrumentation studies, has been performed by an international consortium consisting of institutes from France,
Netherlands, United Kingdom and Italy. All three main science themes of the E-ELT are covered by this instrument:
Planets and Stars; Stars and Galaxies; Galaxies and Cosmology.
This paper gives an overview of the OPTIMOS-EVE project, describing the science cases, top level requirements, the
overall technical concept and the project management approach. It includes a description of the consortium, highlights of
the science drivers and resulting science requirements, an overview of the instrument design and telescope interfaces, the
operational concept, expected performance, work breakdown and management structure for the construction of the
instrument, cost and schedule.
Poster Session I
Converting a liquid nitrogen-cooled camera to closed-cycle cooling
Show abstract
The detector for the ESPaDOnS spectrograph at the Canada-France-Hawaii Telescope (CFHT) is a CCD42-90 4.5kx2k
CCD from e2v Industries in a liquid nitrogen cooled GL Scientific cryostat. This paper describes the conversion of this
camera to closed-cycle cooling using a Polycold® cryogenic refrigeration system. Topics covered include vibration
analysis, positional stability of the image plane, cool-down characteristics, PLC integration, and annual operational
overheads for both systems.
Integration and characterization of HAWAII-1RG detector with FORCAST fast-readout electronics for LMIRcam
Show abstract
The L/M-band Infrared Camera (LMIRcam) is a first-generation imager being constructed for the Large Binocular
Telescope Interferometer, operating at 3-5 μm. Given the high sky background at these wavelengths, an
FPGA-based controller provides high-speed, flexible data acquisition. Originally designed for FORCAST, a mid-
IR camera/spectrograph built by Cornell University, the controller was modified to interface with LMIRcam's
Teledyne HAWAII-1RG 1024×1024 array. In order to facilitate the different operating modes and increased array
size, we have developed a modified version of the FORCAST device driver, reconfigured the FPGAs, altered the
control software, and plan to implement a window mode.
Readout electronics for the Dark Energy Camera
Show abstract
The goal of the Dark Energy Survey (DES) is to measure the dark energy equation of state parameter with four
complementary techniques: galaxy cluster counts, weak lensing, angular power spectrum and type Ia supernovae. DES
will survey a 5000 sq. degrees area of the sky in five filter bands using a new 3 deg2 mosaic camera (DECam) mounted
at the prime focus of the Blanco 4-meter telescope at the Cerro-Tololo International Observatory (CTIO). DECam is a
~520 megapixel optical CCD camera that consists of 62 2k x 4k science sensors plus 4 2k x 2k sensors for guiding. The
CCDs, developed at the Lawrence Berkeley National Laboratory (LBNL) and packaged and tested at Fermilab, have
been selected to obtain images efficiently at long wavelengths. A front-end electronics system has been developed
specifically to perform the CCD readout. The system is based in Monsoon, an open source image acquisition system
designed by the National Optical Astronomy Observatory (NOAO). The electronics consists mainly of three types of
modules: Control, Acquisition and Clock boards. The system provides a total of 132 video channels, 396 bias levels and
around 1000 clock channels in order to readout the full mosaic at 250 kpixel/s speed with 10 e- noise performance.
System configuration and data acquisition is done by means of six 0.8 Gbps optical links. The production of the whole
system is currently underway. The contribution will focus on the testing, calibration and general performance of the full
system in a realistic environment.
Hyper Suprime-Cam: development of the CCD readout electronics
Show abstract
Hyper Suprime-Cam (HSC) employs 116 of 2k×4k CCDs with 464 signal outputs in total. The image size
exceeds 2 GBytes, and the data can be readout every 10 seconds which results in the data rate of 210 Mbytes /
sec. The data is digitized to 16-bit. The readout noise of the electronics at the readout time of 20 seconds is
~0.9 ADU, and the one with CCD is ~1.5 ADU which corresponds to ~4.5 e. The linearity error fits within ±
0.5 % up to 150,000 e. The CCD readout electronics for HSC was newly developed based on the electronics
for Suprime-Cam. The frontend electronics (FEE) is placed in the vacuum dewar, and the backend electronics
(BEE) is mounted on the outside of the dewar on the prime focus unit. The FEE boards were designed to
minimize the outgas and to maximize the heat transfer efficiency to keep the vacuum of the dewar. The BEE
boards were designed to be simple and small as long as to achieve the readout time within 10 seconds. The
production of the system has been finished, and the full set of the boards are being tested with several CCDs
installed in the HSC dewar. We will show the system design, performance, and the current status of the
development.
Implementation of the control electronics for KMOS instrument
Show abstract
The KMOS Instrument is built to be one of the second generation VLT instruments. It is a highly complex multi-object
spectrograph for the near infrared. Nearly 60 cryogenic mechanisms have to be controlled. This includes 24 deployable
Pick-Off arms, three filter and grating wheels as well as three focus stages and four lamps with an attenuator wheel.
These mechanisms and a calibration unit are supervised by three control cabinets based on the VLT standards. To follow
the rotation of the Nasmyth adaptor the cabinets are mounted into a Co-rotating structure. The presentation will highlight
the requirements on the electronics control and how these are met by new technologies applying a compact and reliable
signal distribution. To enable high density wiring within the given space envelope flex-rigid printed circuit board designs
have been installed. In addition an electronic system that detects collisions between the moving Pick-Off arms will be
presented for safe operations. The control system is designed to achieve two micron resolution as required by optomechanical
and flexure constraints. Dedicated LVDT sensors are capable to identify the absolute positions of the Pick-
Off arms. These contribute to a safe recovery procedure after power failure or accidental collision.
An optical frequency comb for infrared spectrograph calibration
Show abstract
The search for extrasolar planets is an exciting new field of astronomy. Since detection of a planet orbiting the
sun-like star 51 Peg,1 the field of planet finding has pushed the limits of sensitivity and accuracy in astronomical
photometry and spectroscopy. To date 455 exoplanets have been detected*, of which the radial velocity technique
is responsible for nearly 80%.2 Radial velocity measurements are also an important complement to photometric
missions such as Kepler and CoRoT, which survey vast numbers of stars simultaneously but which require follow
up measurements for positive identification of planets.
The chief objective in the search for exoplanets is the identification of habitable Earth-like planets in close
proximity to our solar system. Of the currently detected exoplanets, only a few are Earth-like,3 the vast majority
being giants in close orbits. While it is possible that these planets are the most common type, it is likely that
an inherent selection bias in planet finding techniques is the cause. Simply, large radial velocity shifts and
high contrast occultations are the most detectable by radial velocity spectroscopy and photometry, and so we
primarily observe planets capable of inducing them.
Comprehensive transient-state study for CARMENES NIR high-thermal stability
Show abstract
CARMENES has been proposed as a next-generation instrument for the 3.5m Calar Alto Telescope. Its objective is
finding habitable exoplanets around M dwarfs through radial velocity measurements (m/s level) in the near-infrared.
Consequently, the NIR spectrograph is highly constraint regarding thermal/mechanical requirements. Indeed, the
requirements used for the present study limit the thermal stability to ±0.01K (within year period) over a working
temperature of 243K in order to minimise radial velocity drifts. This can be achieved by implementing a solution based
on several temperature-controlled rooms (TCR), whose smallest room encloses the vacuum vessel which houses the
spectrograph's optomechanics.
Nevertheless, several options have been taken into account to minimise the complexity of the thermal design: 1) Large
thermal inertia of the system, where, given a thermal instability of the environment (typically, ±0.1K), the optomechanical
system remains stable within ±0.01K in the long run; 2) Environment thermal control, where thermal
stability is ensured by controlling the temperature of the environment surrounding the vacuum vessel.
The present article also includes the comprehensive transient-state thermal analyses which have been implemented in
order to make the best choice, as well as to give important inputs for the thermal layout of the instrument.
FOROS: Fresnel optical propagation code for SPHERE
Show abstract
SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) is VLT instrument for the discovery and
study of new extra-solar giant planets orbiting nearby stars by direct imaging of their circumstellar environment.
SPHERE is a complex instrument containing more than 50 optical surfaces. The optical imperfections of each of
these surfaces might influence the final contrast. SPHERE has several observing modes in Visible and Infrared,
and therefore several optical paths.
FOROS is an end-to-end optical propagation code for SPHERE, which includes almost all surfaces of the
instrument. It models the instrument by the sequential blocks: VLT, Foreoptics, Corrective Optics, Coronagraph
and so on, such that the beam quality can be studied at several selected locations. The Vis and IR paths are
separated in the model. It incorporates the real data of surface measurement, according to the availability of this
data. Each surface error can be switched on and off; therefore the influence of each surface on the contrast can be
studied independently.
FOROS is an IDL-PROPER-based code, the main power of which is Fresnel propagation. Therefore it represents
a numerical tool to study the Fresnel diffraction effects in SPHERE. In the paper we describe the structure and
philosophy of the code. The phase screens are not yet implemented.
High contrast imaging with IRDIS near infrared polarimeter
Show abstract
The ESO planet-finder VLT instrument SPHERE (Spectro-Polarimetric High-contrast Exoplanet
REsearch), scheduled for first light in 2011, aims to detected and characterize giant extra-solar
planet and the circumstellar environments in the very close vicinity of bright stars. The extreme
brightness contrast and small angular separation between the planets or disks and their parent stars
have so far proven very challenging. SPHERE will meet this challenge by using an extreme AO
system, stellar coronagraphs, an infrared dual band and polarimetric imager called IRDIS, an integral
field spectrograph, and a visible polarimetric differential imager called ZIMPOL. Additional smart
imaging techniques such has differential imaging and differential polarimetry will be also included
to cancel out the light from the parent star and reach typical contrasts of 10-5. We describe here the
performances and the detection limit of IRDIS polarimetric mode for imaging extended stellar
environments.
The performance of the calibration module for SPHERE
Show abstract
One of the main challenges to obtain the contrast of >15mag targeted by the extra-solar planet imager SPHERE lies
in the calibration of all the different elements participating in the final performance. The Adaptive Optics (AO)
system and its three embedded loops, the coronagraphs, the Near Infrared (NIR) dual band imager, the NIR integral
field spectrograph, the NIR spectrograph, the visible high accuracy polarimeter and the visible imager all require
sophisticated calibration. The calibration process relies on a specific complex calibration module that provides the
different sources across the spectrum (500-2320nm) with the stabilities and precisions required and positions them
when the need to be. This calibration module has just passed all verification tests and its performance is now well
characterized. Its design and performance is the object of this article.
Manufacturing and integration of the IRDIS dual imaging camera and spectrograph for SPHERE
Show abstract
SPHERE is a planet hunting instrument for the VLT 8m telescope in Chile whose prime objective is the discovery and
characterization of young Jupiter-sized planets outside of the solar system. It is a complex instrument, consisting of an
extreme Adaptive Optics System (SAXO), various coronagraphs, an infrared differential imaging camera (IRDIS), an
infrared integral field spectrograph (IFS) and a visible differential polarimeter (ZIMPOL). The performance of the IRDIS
camera is directly related to various wavefront error budgets of the instrument, in particular the differential aberrations
occurring after separation of the two image beams. We report on the ongoing integration and testing activities in terms of
optical, mechanical, and cryo-vacuum instrument parts. In particular, we show results of component level tests of the
optics and indicate expected overall performance in comparison with design-level budgets. We also describe the plans
for instrumental performance and science testing of the instrument, foreseen to be conducted during coming months.
Comparison of methods for detection and characterization of exoplanets with SPHERE/IRDIS
Show abstract
SPHERE is a second generation instrument for the Very Large Telescope (VLT) which will aim at directly
detecting the intrinsic flux of young giant exoplanets thanks to a dedicated extreme adaptive optics system
and coronagraphs. Exoplanet detection in the near-infrared will be performed in parallel with an integral
field spectrograph and a differential imager, IRDIS. IRDIS main mode for exoplanet detection will be Dual-
Band Imaging (DBI) where two images are acquired simultaneously at close wavelengths around expected sharp
features in cold planetary objects spectra. We present here the end-to-end simulations performed to obtain
realistic data for IRDIS in DBI mode with temporal evolution of the quasi-static speckle pattern. Data cubes
have been generated to represent 4 hour observations in IRDIS filter pairs for various star magnitudes and planets
at angular separations from 0."2 to 2".0. Using this unique set of data, we present a comparison of various data
analysis methods for high-contrast imaging with IRDIS in DBI mode both in terms of detection limits and of
estimation of the exoplanet flux after speckle noise attenuation.
Halftoning for high-contrast imaging: design, analysis, and testing of microdot coronagraphs for the SPHERE and EPICS instruments
Show abstract
Controlling the amplitude of light is crucial for many scientific applications, such as imaging systems, astronomical
instruments, optical testing, or laser physics. We provide an overview of the halftoning technique - the process of
displaying a continuous image with binary dots - for application to coronagraphy. Customized filters with spatially
varying transmission are produced using a binary array of metal pixels (namely microdot masks) that offers excellent
control of the local transmission, with intrinsic achromaticity. Applications, design guidelines, and tests of near-IR
prototypes for both pupil and focal plane coronagraphic devices are presented in the context of the VLT-SPHERE and EELT
EPICS instruments.
Performance characterization of the HiCIAO instrument for the Subaru Telescope
Show abstract
HiCIAO is a near-infrared, high contrast instrument which is specifically designed for searches and studies for
extrasolar planets and proto-planetary/debris disks on the Subaru 8.2 m telescope. A coronagraph technique
and three differential observing modes, i.e., a dual-beam simultaneous polarimetric differential imaging mode,
quad-beam simultaneous spectral differential imaging mode, and angular differential imaging mode, are used
to extract faint objects from the sea of speckle around bright stars. We describe the instrument performances
verified in the laboratory and during the commissioning period. Readout noise with a correlated double sampling
method is 15 e- using the Sidecar ASIC controller with the HAWAII-2RG detector array, and it is as low as 5 e-
with a multiple sampling method. Strehl ratio obtained by HiCIAO on the sky combined with the 188-actuator
adaptive optics system (AO188) is 0.4 and 0.7 in the H and K-band, respectively, with natural guide stars that
have R ~ 5 and under median seeing conditions. Image distortion is correctable to 7 milli-arcsec level using
the ACS data as a reference image. Examples of contrast performances in the observing modes are presented
from data obtained during the commissioning period. An observation for HR 8799 in the angular differential
imaging mode shows a clear detection of three known planets, demonstrating the high contrast capability of
AO188+HiCIAO.
Data reduction pipeline for the Gemini Planet Imager
Show abstract
The Gemini Planet Imager (GPI) high-contrast adaptive optics system, which is currently under construction
for Gemini South, has an IFS as its science instrument. This paper describes the data reduction pipeline of the
GPI science instrument. Written in IDL, with a modular architecture, this pipeline reduces an ensemble of highcontrast
spectroscopic or polarimetric raw science images and calibration data into a final dataset ready for
scientific analysis. It includes speckle suppression techniques such as angular and spectral differential imaging
that are necessary to achieve extreme contrast performances for which the instrument is designed. This paper
presents also raw GPI IFS simulated data developed to test the pipeline.
An apodizing phase plate coronagraph for VLT/NACO
Show abstract
We describe a coronagraphic optic for use with CONICA at the VLT that provides suppression of diffraction
from 1.8 to 7 λ/D at 4.05 microns, an optimal wavelength for direct imaging of cool extrasolar planets. The
optic is designed to provide 10 magnitudes of contrast at 0.2 arcseconds, over a "D" shaped region in the image
plane, without the need for any focal plane occulting mask.
An eight-octant phase-mask coronagraph for the Subaru coronagraphic extreme AO (SCExAO) system: system design and expected performance
Show abstract
An eight-octant phase-mask (EOPM) coronagraph is one of the highest performance coronagraphic concepts, and attains
simultaneously high throughput, small inner working angle, and large discovery space. However, its application to
ground-based telescopes such as the Subaru Telescope is challenging due to pupil geometry (thick spider vanes and large
central obstruction) and residual tip-tilt errors. We show that the Subaru Coronagraphic Extreme Adaptive Optics
(SCExAO) system, scheduled to be installed onto the Subaru Telescope, includes key technologies which can solve these
problems. SCExAO uses a spider removal plate which translates four parts of the pupil with tilted plane parallel plates.
The pupil central obstruction can be removed by a pupil remapping system similar to the PIAA optics already in the
SCExAO system, which could be redesigned with no amplitude apodization. The EOPM is inserted in the focal plane to
divide a stellar image into eight-octant regions, and introduces a π-phase difference between adjacent octants. This
causes a self-destructive interference inside the pupil area on a following reimaged pupil plane. By using a reflective
mask instead of a conventional opaque Lyot stop, the stellar light diffracted outside the pupil can be used for a
coronagraphic low-order wave-front sensor to accurately measure and correct tip-tilt errors. A modified inverse-PIAA
system, located behind the reimaged pupil plane, is used to remove off-axis aberrations and deliver a wide field of view.
We show that this EOPM coronagraph architecture enables high contrast imaging at small working angle on the Subaru
Telescope. Our approach could be generalized to other phase-mask type coronagraphs and other ground-based telescopes.
Fabrication and testing of phase masks for optical vortex coronagraph to observe extrasolar planets
Show abstract
The optical vortex coronagraph (OVC) is an innovative instrument that can be applied to both space and groundbased
telescopes for direct imaging of planets around bright stars. OVC rejects the light of the on-axis star without
altering that of off-axis sources, means of a spiral phase plate (SPP) used as a phase modyfing device (PMD).
We present the fabrication process made by lithographic nanofabrication and tests for the characterization of
two different high-quality SPPs.
A 64 Mpixel camera for the Wendelstein Fraunhofer Telescope Nasmyth wide-field port: WWFI
Show abstract
Ludwig-Maximilians-Universit¨at M¨unchen operates an astrophysical observatory on the summit of Mt. Wendelstein1
which will be equipped with a modern 2m-class, robotic telescope.2 One Nasmyth port of the new
Fraunhofer telescope is designed to sustain the excellent (< 0.8" median) seeing of the site [1, Fig. 1] over a FOV
of 0.2 deg2 utilizing three-element transmissive field corrector optics for optical wavebands. It will be equipped
with a camera built around a customized 64 MPixel Mosaic (Spectral Instruments, 4 × (4k)2 15μm e2v CCDs).
TheWendelsteinWide Field Imager has two filter wheels with eight slots each (SDSS3 [ugriz] + eight still free)
as well as two off-axis guiding units (two FLI Microline with 2k Fairchild CCDs on differential focus stages). A
Bonn Shutter4 ensures high precision photometric exposures. An option to either insert a low dispersion grating
(for field spectroscopy) or support a wave front sensor probe allows for further expansion of the camera. EMI-safe
housing has to overcome the emission of a close by 0.5MW radio station. Special care has been taken to design
a very low ghost budget of the overall system to allow for low-surface brightness applications (e.g. weak lensing
surveys).
The PAU camera
Show abstract
The Physics of the Accelerating Universe (PAU) collaboration aims at conducting a competitive cosmology experiment.
For that purpose it is building the PAU Camera (PAUCam) to carry out a wide area survey to study dark energy.
PAUCam has been designed to be mounted at the prime focus of the William Herschel Telescope with its current optical
corrector that delivers a maximum field of view of ~0.8 square degrees. In order to cover the entire field of view
available, the PAUCam focal plane will be populated with a mosaic of eighteen CCD detectors. PAUCam will be
equipped with a set of narrow band filters and a set of broad band filters to sample the spectral energy distribution of
astronomical objects with photometric techniques equivalent to low resolution spectroscopy. In particular it will be able
to determine the redshift of galaxies with good precision and therefore conduct cosmological surveys. PAUCam will also
be offered to the broad astronomical community.
IMAKA: imaging from MAuna KeA optical design
Show abstract
The 'IMAKA (Imaging from MAuna KeA) instrument is a wide field visible light imager incorporating Ground Layer
Adaptive Optics (GLAO) to take maximum advantage of the excellent seeing available at the Canada-France-Hawaii
Telescope (CFHT). It requires better than 0.3" image quality simultaneously over a total field of view of approximately
one square degree (~3 x 10-4 sr). This requirement along with other criterions and constraints raises a challenge for
optical design. The advent of orthogonal transfer (OT) CCDs allows the tip-tilt portion of the atmospheric correction to
be performed at the science detector itself. 'IMAKA will take full advantage of the large array mosaics of OTCCDs.
Since the size of the adaptive mirror would drive the cost and hence implementation of the overall 'IMAKA instrument,
a review of possible optical design configurations which minimize the size (diameter) of the deformable mirror is
undertaken. A promising design was obtained and developed in more detail. This all reflective system is described along
with its predicted optical performance. An opto-mechanical design concept was developed around this nominal optical
design which takes into account various constraints due to its required location on the top end of the Canada France
Hawaii Telescope. The design concept is feasible and meets the optical performance requirements.
Design of AMASING: a new aperture masking instrument for high-resolution imaging at optical wavelengths
Show abstract
We describe the science goals, optical and mechanical design, software control, data reduction and current status
of a new aperture masking instrument for meter class telescopes. AMASING (Aperture Masking And Speckle
ImagiNG) was designed to be a flexible Nasmyth mounted platform for high resolution astronomy at optical
wavelengths. The instrument is self guiding and includes cameras for target acquisition and guiding, masked
pupil viewing and high frame rate data collection.
Study of the image quality and stray light in the critical design phase of the Compact Echelle Spectrograph for Aeronomical Research (CESAR)
Show abstract
The success of the high resolution nightglow studies conducted with the Keck telescopes on Mauna Kea and the Very
Large Telescopes in Chile led to the design of the Compact Echelle Spectrograph for Aeronomical Research (CESAR).
This is an echelle spectrograph with grating post-dispersion that will be dedicated to nightglow studies at high spectral
resolution (R ~ 20000) between 300-1000 nm, and that will be easily deployable at different sites. The development of
CESAR is conducted by SRI International, and INO is involved in the optical design and integration of the spectrograph
camera, whose all-spherical form is based on the camera of the HIRES spectrograph at the Keck I telescope. The
detailed optical design is used to calculate the position of the spectral elements on the detector, predict their image
quality, and estimate the level of stray light. This paper presents the methodology used in these analyses.
A new image acquisition system for the Kitt Peak National Observatory Mosaic-1 imager
Show abstract
A project is currently underway to upgrade the Kitt Peak National Observatory (KPNO) Mosaic-1 Imager, an 8192 x
8192 pixel CCD array used on the Mayall 4-meter and WIYN 0.9-meter telescopes. Mosaic-1 has been a heavily
subscribed instrument by the US astronomical community since it was commissioned more than a decade ago. In recent
years, however, the reliability and efficiency of Mosaic-1 has declined due to aging and failing components. In addition,
servicing has become more and more difficult as spare parts are used up, replacement parts become unavailable, and
technical expertise for the out-dated controller technology diminishes. The Mosaic-1 upgrade project addresses these
reliability and servicing concerns by replacing the CCDs with modern detectors and replacing the controllers with a
MONSOON image acquisition system. The upgrade will also enhance the scientific productivity of the instrument
through reduced read times, lower read noise, and improved quantum efficiency. We will describe the project status, the
technical requirements related to the installation of new CCD detectors and MONSOON controllers, the configuration of
the system, and integration of the system into the existing instrument and telescope environments.
MAIA: a rapid three-channel photometry CCD instrument for asteroseismology observations
Show abstract
The Mercator Advanced Imager for Asteroseismology (MAIA) is being designed particularly for asteroseismology
of hot subdwarf stars. In order to achieve the required precision on the pulsation amplitude ratios, the photometric
variations must be measured simultaneously in several bands with respect to constant reference stars in the
field. MAIA is an optical imager to observe simultaneously in three color bands, corresponding approximately
with an SDSS u, g, r+i+z photometric system. The fully dioptric design uses a common collimator, two dichroic
beam splitters (cut-offs at 390nm and 550nm) and three cameras. MAIA covers a wide field of view (FoV)
of 9.4' x 14.1' with a sampling of 0.27"/pix on the 1.2m Mercator Telescope. When replacing the collimator
and with a modest reduction of the FoV, its host can also be used on larger telescopes. Each camera holds a
fast-frame-transfer charge coupled device (CCD), cooled by three four-stage Peltier elements to -70 °C. The
mechanical design minimizes structural flexure. Selected optical elements are mounted in quasi-isostatic lens
mounts to minimize the effects of temperature variations.
A radiometric all-sky infrared camera (RASICAM) for DES/CTIO
Peter M. Lewis,
Howard Rogers,
Rafe H. Schindler
Show abstract
A novel radiometric all-sky infrared camera [RASICAM] has been constructed to allow automated real-time quantitative
assessment of night sky conditions for the Dark Energy Camera [DECam] located on the Blanco Telescope at the Cerro
Tololo Inter-American Observatory in Chile. The camera is optimized to detect the position, motion and optical depth of
thin, high (8-10km) cirrus clouds and contrails by measuring their apparent temperature above the night sky background.
The camera system utilizes a novel wide-field equiresolution catadioptic mirror system that provides sky coverage of 2π
azimuth and 14-90° from zenith. Several new technological and design innovations allow the RASICAM system to
provide unprecedented cloud detection and IR-based photometricity quantification. The design of the RASICAM system
is presented.
QUOTA: the prototype camera for the WIYN one degree imager (ODI)
Show abstract
QUOTA is an 8Kx8K (16'x16') optical imager using four 4Kx4K orthogonal transfer CCDs arrays (OTAs). Each OTA
has 64 nearly independent CCDs having 480x494 12μm pixels. By reading out several of the CCDs rapidly (20 Hz), the
centroids of the stars in those CCDs can be used to measure image motion due to atmospheric effects, telescope shake,
and guide errors. Motions are fed back to the remaining 250 CCDs that continue to integrate normally, allowing a shift
of the collecting charge packets so that they always fall under the moving star images, thereby effecting low order
adaptive optics tip/tilt correction in the silicon to improve image quality. As a bonus, the stars that are read rapidly can
be studied for high speed photometric variability.
QUOTA was conceived to be a prototype for WIYN's 32Kx32K One Degree Imager (ODI), providing a means to test
and advance the technical developments for the larger imager (e.g., detectors, controllers, optics, coatings, cooling, and
software). QUOTA will have been to the WIYN 3.5-m telescope only twice in its current configuration, but it provided
a wealth of information that has been useful to the engineering of ODI. We focus on the areas in which ODI has
benefited from QUOTA in this report.
FastCam optomechanical system design and manufacture
Show abstract
FastCam is an instrument jointly developed by the Instituto de Astrofísica de Canarias (IAC) and the Universidad
Politécnica de Cartagena (UPCT), designed to obtain high spatial resolution images in the optical wavelength range from
ground-based telescopes (http://www.iac.es/proyecto/fastcam and
http://www.iac.es/telescopes/Manuales/manualfastcam.pdf). The instrument is equipped with a very low noise and very
fast readout speed EMCCD camera which provides short exposure images to an FPGA-based processor which performs
the selection, recenterg and combination of images in real-time (applying Lucky Imaging techniques) to provide
diffraction limited resolution images in 1-4 m class telescopes from 500 to 1100 nm.
IDOM has contributed to this new state-of-the-art instrument with the design of an optomechanical system conceived to
maximize the image scale stability of the system for astrometry. The combination of aluminum plates, carbon fiber
(CFRP) rods and stainless steel mounts in the optical bench defines an athermalized and stiff design to meet the
requirements of thermal and mechanical stability.
This work has been done with the support of the Aerospace Subprogramme of the Spanish Centre for the Development
of Industrial Technology (CDTI) and the INTEK programme of the Basque Development Agency (SPRI).
Hyper Suprime-Cam: camera design
Show abstract
Hyper Suprime-Cam (HSC) is the next generation wide-field imager for the prime focus of Subaru Telescope,
which is scheduled to receive its first light in 2011. Combined with a newly built wide-field corrector, HSC
covers 1.5 degree diameter field of view with 116 fully-depleted CCDs. In this presentation, we summarize the
details of the camera design: the wide-field corrector, the prime focus unit, the CCD dewar and the peripheral
devices. The wide-field corrector consists of 5 lenses with lateral shift type doublet ADC element. The novel
design guarantees the excellent image quality (D80 <0".3) over the field of view. On the focal plane, 116 CCDs
are tiled on the cold plate which is made of Silicon Carbide (SiC) and cooled down to -100 degrees by two pulse
tube coolers. The system is supported by the prime focus unit which provides a precise motion of the system to
align the wide-field corrector and the CCD dewar to the optical axis of the telescope.
System architecture of the Dark Energy Survey Camera readout electronics
Show abstract
The Dark Energy Survey makes use of a new camera, the Dark Energy Camera (DECam). DECam will be installed in the Blanco 4M telescope at Cerro Tololo Inter-American Observatory (CTIO). DECam is presently under construction
and is expected to be ready for observations in the fall of 2011. The focal plane will make use of 62 2Kx4K and 12
2kx2k fully depleted Charge-Coupled Devices (CCDs) for guiding, alignment and focus. This paper will describe design
considerations of the system; including, the entire signal path used to read out the CCDs, the development of a custom
crate and backplane, the overall grounding scheme and early results of system tests.
The Large Binocular Telescope mid-infrared camera (LMIRcam): final design and status
Show abstract
We report on the final design and the fabrication status of LMIRcam - a mid-infrared imager/spectrograph that will
operate behind the Large Binocular Telescope Interferometer (LBTI) primarily at wavelengths between 3 and 5um (the
astronomical L- and M-bands). Within LMIRcam a pair of diamond-turned biconic mirrors re-images a ten arcsecond
square field onto a 1024x1024 HAWAII-1RG 5.1um cutoff array. The re-imaging optics provide two pupil planes for
the placement of filters and grisms as well as an intermediate image plane. Flexible readout electronics enable operating
modes ranging from high frame rate broadband imaging at the longest wavelengths to low background R=400
spectroscopy at shorter wavelengths. The LBTI will provide LMIRcam with a diffraction limited two-mirror PSF with
first null dictated by the 14.4 meter separation of the two LBT mirror centers (22.8 meter baseline from edge to edge).
Testing the Dark Energy Camera on a telescope simulator
Show abstract
The Dark Energy Camera is a new prime-focus instrument to be delivered to the Blanco 4-meter telescope at the Cerro
Tololo Inter-American Observatory (CTIO) in 2011. Construction is in-progress at this time at Fermilab. In order to
verify that the camera meets technical specifications for the Dark Energy Survey and to reduce the time required to
commission the instrument while it is on the telescope, we are constructing a "Telescope Simulator" and performing full
system testing prior to shipping to CTIO. This presentation will describe the Telescope Simulator and how we use it to
verify some of the technical specifications.
First Paschen alpha imaging from the ground: the first light of Atacama Near-Infrared Camera on the miniTAO 1m telescope
Show abstract
We have developed a near infrared camera called ANIR (Atacama Near InfraRed camera) for the University of
Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in northern Chile.
The camera is based on a PACE HAWAII-2 array with an Offner relay optics for re-imaging, and field of view
is 5.
3 × 5.
3 with pixel scale of 0.
31/pix. It is also capable of optical/infrared simultaneous imaging by inserting
a dichroic mirror before the focal plane. The high altitude and extremely low water vapor (PWV=0.5mm) of
the site enables us to perform observation of hydrogen Paschenα (Paα) emission line at 1.8751 μm. The first
light observation was carried out in July 2009, and we have successfully obtained Paα images of the Galactic
center using the N1875 narrow-band filter. This is the first success of Paα imaging of a Galactic object from a
ground based telescope. System efficiencies for the broad-band filters are measured to be 15% at the J-band and
30% at Ks, while that of the N1875 narrow-band filter, corresponding to Paα; wavelength, varies from 8 to 15%,
which may be caused by fluctuation of the atmospheric transmittance. ATRAN simulation suggests that this
corresponds to PWV of 0.3 - 1.5mm, consistent with previous results of the site testing. Measured seeing size
is median ~0.
8, corresponding to the real seeing value of 0.
6 - 0.
8. These results demonstrates the excellent
capability of the site for infrared observations.
AMICA: the NIR/MIR camera for automatic astronomical observations from Dome C, Antarctica
Show abstract
AMICA is a double-armed camera designed to perform NIR/ MIR (2-28 μm) Astronomy from Antarctica. It will be
installed at Dome C in 2010-2011. An overview of the instrument is given, with attention to the following features: 1)
Winterization: AMICA has been tested under Antarctic conditions to be operated in severe environments; 2) Automation:
AMICA does not require human intervention; 3) Fast acquisition: AMICA can get images with exposure times less than
3 msec; 4) Survey-mode observations: the low background in Antarctica allows AMICA to have FOVs of 2.29 arcmin
(NIR) and 2.89 arcmin (MIR), without saturation even with wide-band filters.
The Palomar Transient Factory Survey Camera: first year performance and results
Show abstract
The Palomar Transient Factory (PTF) is a new fully-automated, wide-field survey conducting a systematic exploration
of the optical transient sky. The transient survey is performed using a new 8.1 square degree, 101 megapixel camera
installed on the 48-inch Samuel Oschin Telescope at Palomar Observatory. The PTF Camera achieved first light at the
end of 2008, completed commissioning in July 2009, and is now in routine science operations. The camera is based on
the CFH12K camera, and was extensively modified for use on the 48-inch telescope. A field-flattening curved window
was installed, the cooling system was re-engineered and upgraded to closed-cycle, custom shutter and filter exchanger
mechanisms were added, new custom control software was written, and many other modifications were made. We here
describe the performance of these new systems during the first year of Palomar Transient Factory operations, including
a detailed and long term on-sky performance characterization. We also describe lessons learned during the construction
and commissioning of the upgraded camera, the photometric and astrometric precision currently achieved with the PTF
camera, and briefly summarize the first supernova results from the PTF survey.
Performance of the WIYN high-resolution infrared camera
Show abstract
The WIYN High Resolution Infrared Camera (WHIRC) has been a general-use instrument at the WIYN telescope on
Kitt Peak since 2008. WHIRC is a near-infrared (0.8 - 2.5 μm) camera with a filter complement of J, H, Ks broadband
and 10 narrowband filters, utilizing a 2048 × 2048 HgCdTe array from Raytheon's VIRGO line, developed for the
VISTA project. The compact on-axis refractive optical design makes WHIRC the smallest near-IR camera with this
capability. WHIRC is installed on the WIYN Tip-Tilt Module (WTTM) port and can achieve near diffraction-limited
imaging with a FWHM of ~0.25 arcsec at Ks with active WTTM correction and routinely delivers ~0.6 arcsec FWHM
images without WTTM correction. During its first year of general use operation at WIYN, WHIRC has been used for
high definition near-infrared imaging studies of a wide range of astronomical phenomena including star formation
regions, stellar populations and interstellar medium in nearby galaxies, high-z galaxies and transient phenomena. We
discuss performance and data reduction issues such as distortion, pupil ghost, and fringe removal and the development of
new tools for the observing community such as an exposure time calculator and data reduction pipeline.
Development of a new mid-infrared instrument for the TAO 6.5-m Telescope
Show abstract
Ground-based mid-infrared observations have two distinct advantages over space observations despite relatively lower
sensitivity. One is the high spatial resolution and the other is the monitoring capability. These advantages can be
emphasized particularly for the next coming ground-based infrared project University of Tokyo Atacama Observatory
(TAO). Thanks to the low water vapor of the TAO site (5,640m) and the large aperture of the telescope (6.5meter), we
can observe at 30 micron with a spatial resolution of 1 arcsec. It is about ten times higher than that of current space
telescopes. The TAO is also useful for monitoring observations because of the ample observing time.
To take these advantages we are now developing a new mid-infrared infrared instrument for the TAO 6.5-meter
telescope. This covers a wide wavelength range from 2 to 38 micron with three detectors (Si:As, Si:Sb, and InSb).
Diffraction limited spatial resolution can be achieved at wavelengths longer than 7 micron. Low-resolution spectroscopy
can also be carried out with grisms. This instrument equips a newly invented "field stacker" for monitoring observations.
It is an optical system that consists of two movable pick-up mirrors and a triangle shaped mirror, and combine two
discrete fields of the telescope into camera's field of view. It will enable us to apply a differential photometry method
and dramatically improve the accuracy and increase the feasibility of the monitoring observations at the mid-infrared
wavelengths.
3kk: the Optical-NIR Multi-Channel Nasmyth Imager for the Wendelstein Fraunhofer Telescope
Show abstract
The Ludwig-Maximilians-Universit¨at M¨unchen operates an astrophysical observatory on the summit of Mt.
Wendelstein1 which will be equipped with a modern 2m-class, robotic telescope.2 One Nasmyth port of the new
Fraunhofer telescope is designed to deliver the excellent (< 0.8" median) seeing of the site [1, Fig. 1] for a smaller
FoV of 60 arcmin2 without any corrector optics at optical and NIR wavebands. Thus, it will be optimized for
fast multi-wavelength follow-up observations of targets of opportunities (e.g. Gamma-Ray-bursts) or efficient
photometric redshift determinations of huge numbers of galaxy clusters identified in optical (PanSTARRS), SZ
(Planck) or X-ray (eROSITA) surveys. We present the design of a compact 3 channel camera which serves these
science requirements, built partly from commercially available Fairchild-2k optical CCD3 cameras (Apogee),
coupled with small Bonn Shutters,4 and mounted on commercial high precision linear stages for differential
focusing. A specially designed beam-splitter system maintains the high optical quality. The NIR camera is built
in cooperation with the Institute for Astronomy in Hawaii. The combined operation of this camera with two
spectrographs at the same telescope port has already been presented at SPIE 2008.5
PAUCam filter interchange system
Show abstract
The Physics of the Accelerating Universe (PAU) is a new project whose main goal is to study dark energy surveying the
galaxy distribution. For that purpose we need to determine the galaxy redshifts. The most accurate way to determine the
redshift of a galaxy and measure its spectral energy distribution (SED) is achieved with spectrographs. The PAU
collaboration is building an instrument (PAUCam) devoted to perform a large area survey for cosmological studies using
an alternative approach. SEDs are sampled and redshifts determined using narrow band filter photometry. For efficiency
and manufacturability considerations, the filters need to be placed close to the CCD detector surfaces on segmented filter
trays. The most innovative element of PAUCam is a set of 16 different exchangeable trays to support the filters arranged
in a jukebox-like changing mechanism inside the cryostat. The device is designed to operate within the range of
temperatures from 150K to 300K at the absolute pressure of 10-8mbar, being class-100 compliant.
Focus and alignment using out-of-focus stellar images at the Dark Energy Camera
Aaron Roodman
Show abstract
The focus and alignment system of the prime focus Dark Energy Camera (DECam), for the Dark Energy Survey
at the CTIO 4 meter Blanco telescope, is described. DECam includes eight 2K by 2K CCDs placed 1.5mm
extra- and intra-focally for active control of focus and alignment, as well as for wavefront measurement. We
describe an algorithm for out-of-focus star (donut) image analysis and present results on the use of donuts for
focus and alignment. Results will be presented for both simulated DECam images and for images taken at the
Blanco 4 meter with the current MosaicII camera.
Measuring the flatness of focal plane for very large mosaic CCD camera
Show abstract
Large mosaic multiCCD camera is the key instrument for modern digital sky survey. DECam is an extremely
red sensitive 520 Megapixel camera designed for the incoming Dark Energy Survey (DES). It is consist of sixty
two 4k2k and twelve 2k2k 250-micron thick fully-depleted CCDs, with a focal plane of 44 cm in diameter and
a eld of view of 2.2 square degree. It will be attached to the Blanco 4-meter telescope at CTIO. The DES will
cover 5000 square-degrees of the southern galactic cap in 5 color bands (g, r, i, z, Y) in 5 years starting from
2011.
To achieve the science goal of constraining the Dark Energy evolution, stringent requirements are laid down
for the design of DECam. Among them, the
atness of the focal plane needs to be controlled within a 60-micron
envelope in order to achieve the specied PSF variation limit. It is very challenging to measure the
atness of
the focal plane to such precision when it is placed in a high vacuum dewar at 173 K. We developed two image
based techniques to measure the
atness of the focal plane. By imaging a regular grid of dots on the focal plane,
the CCD oset along the optical axis is converted to the variation the grid spacings at dierent positions on the
focal plane. After extracting the patterns and comparing the change in spacings, we can measure the
atness
to high precision. In method 1, the regular dots are kept in high sub micron precision and cover the whole focal
plane. In method 2, no high precision for the grid is required. Instead, we use a precise XY stage moves the
pattern across the whole focal plane and comparing the variations of the spacing when it is imaged by dierent
CCDs. Simulation and real measurements show that the two methods work very well for our purpose, and are
in good agreement with the direct optical measurements.
Opto-mechanical design of PANIC
Show abstract
PANIC, the Panoramic Near-Infrared Camera, is a new instrument for the Calar Alto Observatory. A 4x4 k detector
yields a field of view of 0.5x0.5 degrees at a pixel scale of 0.45 arc sec/pixel at the 2.2m telescope. PANIC can be used
also at the 3.5m telescope with half the pixel scale. The optics consists of 9 lenses and 3 folding mirrors. Mechanical
tolerances are as small as 50 microns for some elements. PANIC will have a low thermal background due to cold
stops. Read-out is done with MPIA's own new electronics which allows read-out of 132 channels in parallel. Weight
and size limits lead to interesting design features. Here we describe the opto-mechanical design.
Software control and characterization aspects for image derotator of the AO188 system at Subaru
Show abstract
The image derotator is an integral part of the AO188 System at Subaru Telescope. In this article software control,
characterization and integration issues of the image derotator for AO188 System presented. Physical limitations of the
current hardware reviewed. Image derotator synchronization, tracking accuracy, and problem solving strategies to
achieve requirements presented. It's use in different observation modes for various instruments and interaction with the
telescope control system provides status and control functionality. We describe available observation modes along with
integration issues. Technical solutions with results of the image derotator performance presented. Further improvements
and control software for on-sky observations discussed based on the results obtained during engineering observations.
An overview of the requirements, the final control method, and the structure of its control software is shown. Control
limitations and accepted solutions that might be useful for development of other instrument's image derotators presented.
Visible Integral-field Replicable Unit Spectrograph (VIRUS) optical tolerance
Show abstract
The Visible Integral-field Replicable Unit Spectrograph (VIRUS) instrument is made up of 150+ individually compact
and identical spectrographs, each fed by a fiber integral field unit. The instrument provides integral field spectroscopy
from 350 nm to 550 nm of over 33,600 spatial elements per observation, each 1.8 arcsec2 on the sky, at R ~ 700. The
instrument will be fed by a new wide-field corrector (WFC) of the Hobby-Eberly Telescope (HET†) with increased
science field of view as large as 22 arcmin diameter and telescope aperture of 10 m. The construction of the large
number of VIRUS units requires the individual spectrographs be interchangeable at sub-system level and a production
line assembly process be utilized, while meeting the optical performance specification. These requirements pose a strong
emphasis on careful analysis of the manufacturing and alignment tolerances of the unit spectrograph design. In this
paper, we detail the tolerance analysis, and discuss its implication to the optical performance and production of the
VIRUS instrument.
A versatile motion control system for astronomical instrumentation
Show abstract
With steadily increasing telescope sizes and the growing complexity of scientific instruments, there is an ever-growing
demand for improved electronics, controlling all the different optical parts on moving mechanisms. Among competing
requirements are, on one hand, the increasing number of actuators, with high-precision positioning in closed and open
loop, and on the other hand, smaller sizes, low power and restricted heat emission. A specific challenge is
accommodating mechanisms that operate in infrared instrumentation at cryogenic temperatures down to 60 Kelvin. In
this area piezo motors offer promising solutions. To fulfill these different demands a competitive motion control system
has been developed at the Max-Planck-Institut für Astronomie (MPIA) in Heidelberg, Germany. A modular chassis with
standardized boards provides best solutions for extensive tasks. High and low power DC servo motors, brushless DC
servo motors, stepper motors and piezo motors with different technologies are supported. Diversity position feedback
capabilities, like incremental and absolute encoders for non cryogenic and capacitive sensors and resolvers for cryogenic
applications, are provided.
There and back again: sharing a major instrument between hemispheres
Show abstract
As astronomical instruments have increased in complexity, cost and production time, sharing a major instrument
between telescopes has become an attractive alternative to duplication. This requires solving technical and logistical
problems of transportation, transferring operational support knowledge between on-site staffs, and developing effective
responses to in-service problems at a different site. The infrared camera NEWFIRM has been operated for two years on
the 4-m Mayall telescope of Kitt Peak National Observatory in Arizona. We have recently temporarily moved it to the 4-
m Blanco telescope of Cerro Tololo Interamerican Observatory in Chile for a limited period of operation. We describe
here our solutions to the challenges involved in relocating this major in-service cryogenic instrument, with an emphasis
on "lessons learned" to date.
Future development of the PLATO Observatory for Antarctic science
Show abstract
PLATO is a self-contained robotic observatory built into two 10-foot shipping containers. It has been successfully
deployed at Dome A on the Antarctic plateau since January 2008, and has accumulated over 730 days of
uptime at the time of writing. PLATO provides 0.5{1kW of continuous electrical power for a year from diesel
engines running on Jet-A1, supplemented during the summertime with solar panels. One of the 10-foot shipping
containers houses the power system and fuel, the other provides a warm environment for instruments. Two
Iridium satellite modems allow 45 MB/day of data to be transferred across the internet.
Future enhancements to PLATO, currently in development, include a more modular design, using lithium
iron-phosphate batteries, higher power output, and a light-weight low-power version for eld deployment from a
Twin Otter aircraft.
Technologies used in PLATO include a CAN (Controller Area Network) bus, high-reliability PC/104 com-
puters, ultracapacitors for starting the engines, and fault-tolerant redundant design.
Hexabundles: imaging fibre arrays for low-light astronomical applications
Show abstract
We demonstrate for the first time an imaging fibre bundle ("hexabundle") that is suitable for low-light applications in
astronomy. The most successful survey instruments at optical-infrared wavelengths today have obtained data on up to a
million celestial sources using hundreds of multimode fibres at a time fed to multiple spectrographs. But a large fraction
of these sources are spatially extended on the celestial sphere such that a hexabundle would be able to provide
spectroscopic information at many distinct locations across the source. Our goal is to upgrade single-fibre survey
instruments with multimode hexabundles in place of the multimode fibres. We discuss two varieties of hexabundles: (i)
closely packed circular cores allowing the covering fraction to approach the theoretical maximum of 91%; (ii) fused noncircular
cores where the interstitial holes have been removed and the covering fraction approaches 100%. In both cases,
we find that the cladding can be reduced to ~2μm over the short fuse length, well below the conventional ~10λ thickness
employed more generally. We discuss the relative merits of fused/unfused hexabundles in terms of manufacture and
deployment, and present our first on-sky observations.
Experimental investigation of adhesive bond strength between metal and optical glass
Show abstract
Within the general astronomical community as well as at the University of California Observatories, there has been a
long history of using epoxy to mount optics within instruments such as spectrometers and telescopes. The Ken & Gloria
Levy Spectrometer, part of the Automated Planet Finder (APF) telescope located at Mt. Hamilton's Lick Observatory,
relies on epoxy-bonded joints to attach the instrument's large cross-dispersing prism and echelle grating to its Invar
space-frame structure. Design constraints dictated that these large optics each be attached at only three points, and that
the bond areas be as small as possible while maintaining an adequate strength factor of safety. Previous UCO
instruments, such as the Keck Telescopes' primary mirror segments and the ESI Spectrometer, used Hysol's 9313 epoxy
product for this purpose. Concerns over long-term reliability of such joints led us to re-examine this issue. We
empirically investigated the roles played by epoxy selection and techniques such as surface preparation and the use of a
primer, in creating a robust metal-to-glass bond. Bond strength data was generated, leading us to select a previously
unused epoxy, and to implement particular techniques to ensure bond quality. Most notably, we found that bond strength
data as typically reported on adhesive manufacturers' datasheets was not a reliable indicator of long-term bond reliability
between metal and optical glass.
A compact light-weighted and multi-purpose calibration unit for LINC-NIRVANA
Show abstract
Laboratory and on-sky experience suggests that the integration of big astronomical instruments, specially of a
complex interferometric system, is a challenging process. LINC-NIRVANA is the Fizeau interferometric imager
for the Large Binocular Telescope (LBT). Simulating the final operating environment of every system component
has shown how critical is the presence of flexures, vibrations and thermal expansion. Assembling and aligning
the opto-mechanical sub-systems will require an absolute reference which is not affected by static displacements
or positioning errors.
A multi-purpose calibration unit has been designed to ensure the quality of the alignment of optics and
detectors and the reliability of the mechanical setup. This new compact and light-weighted unit is characterized
by sophisticated kinematics, simple mechanical design and composite materials. In addition, the reduced number
of motorized axis improves the stiffness and lowers the angular displacements due to moving parts. The modular
concept integrates several light sources to provide the proper calibration reference for the different sub-systems
of LINC-NIRVANA. For the standard alignment of the optics an absolute reference fiber will be used. For flatfielding
of the detectors the unit provides an integrating sphere, and a special rotating multi-fiber plate (infrared
and visible) is used to calibrate the advanced adaptive optics and the fringe-tracking systems. A module to
control non-common path aberrations (Flattening of Deformable Mirrors) is also provided.
A fiber positioner robot for the Gran Telescopio Canarias
Show abstract
Fiber-fed spectrographs dedicated to observing massive portions of the sky are increasingly being more demanded
within the astronomical community. For all the fiber-fed instruments, the primordial and common problem is the
positioning of the fiber ends, which must match the position of the objects of a target field on the sky. Amongst
the different approaches found in the state of the art, actuator arrays are one of the best. Indeed, an actuator
array is able to position all the fiber heads simultaneously, thus making the reconfiguration time extremely short
and the instrument efficiency high. The SIDE group* at the Instituto de Astrofisica de Andalucia, together with
the industrial company AVS and the University of Barcelona, has been developing an actuator suitable for a large
and scalable array. A real-scale prototype has been built and tested in order to validate its innovative design
concept, as well as to verify the fulfillment of the mechanical requirements. The present article describes both
the concept design and the test procedures and conditions. The main results are shown and a full justification
of the validity of the proposed concept is provided.
Upgrade of Iqueye, a novel photon-counting photometer for the ESO New Technology Telescope
Show abstract
Iqueye is a novel extremely high speed photon-counting photometer for the European Southern Observatory New
Technology Telescope in La Silla (Chile). Iqueye collects the light from the telescope through a few arcsec aperture, and
splits it along four independent channels, each feeding a single photon avalanche diode. The produced count pulses are
collected by a time-to-digital converter board and suitably time-tagged. Thanks to a rubidium oscillator and a GPS
receiver, an absolute rms timing accuracy better than 0.5 ns during one-hour observations can be achieved by postprocessing
the data. The system can sustain a count rate of up to 8 MHz uninterruptedly for an entire night of
observation.
After the first run in January 2009, some improvements have been evidenced and realized: a more practical mechanical
structure, a better optimization of the optical design, an additional filter wheel per each channel, a fifth photon counting
detector for monitoring the sky, a more interactive interface software. The updated Iqueye has been tested in December
2009, and the obtained results showed still better performance. As an example, the light curves of visible pulsars down to
the 25th visible magnitude have been obtained in a few hours of observation.
Introduction to MIOSOTYS: a multiple-object, high-speed photometer
I. Chun Shih,
Alain Doressoundiram,
Yannick Boissel,
et al.
Show abstract
MIOSOTYS is a multiple-object, high-speed photometer. It is currently operating on the 1.93m telescope at
Observatoire de Haute-Provence (OHP), France. The instrument consists of a multi-fibre positioner which can
access maximum 29 targets simultaneously, and an EMCCD camera which is capable of recording low-level light
at high frame rate. This paper will describes the instrument's specifications as well as the performance, i.e.,
signal-to-noise ratio, under the current configuration (ProEM CCD + 1.93m telescope).
MooSci: a lunar scintillometer
Show abstract
MooSci is a linear array of photodiodes that measures time varying intensities of light reflected from the Moon, lunar
scintillation. The covariance between all possible pairs of photodiodes can be used to reconstruct the ground layer
turbulence profile from the ground up to a maximum height roughly determined by the distance between the furthest pair
of detectors. This technique of profile restoration will be used for site testing at various locations. This paper describes
the design of a lunar scintillometer and preliminary results from Las Campanas Peak.
Experimental results from using two laminated film polarizers to make absolute measurements of polarization crosstalk in an optic
Show abstract
In working with polarimeters, it is useful to be able to analyze the level of stress birefringence in the optics of the
polarimeter individually. This birefringence shows up in the polarimeter as a conversion of linear polarization to
circular polarization and vice versa. A method has been developed for using two, low-cost, laminated film polarizers to
make measurements of linear-to-circular polarization conversion in sample optics. Measurements were made on several
optical elements of the ESPaDOnS spectro-polarimeter during the effort to reduce the polarization crosstalk, as well as
on a quarter-wave plate in order to calibrate the measurement.
RINGO2: an EMCCD-based polarimeter for GRB followup
Show abstract
We describe the design and construction of a new novel optical polarimeter (RINGO2) for the Liverpool Telescope.
The instrument is designed for rapid (< 3 minute) followup observations of Gamma Ray Bursts in order to
measure the early time polarization and time evolution on timescales of ~ 1 - 10000 seconds. By using a fast
rotating Polaroid whose rotation is synchronized to control the readout of an electron multiplying CCD eight
times per revolution, we can rebin our data in the time domain after acquisition with little noise penalty, thereby
allowing us to explore the polarization evolution of these rapidly variable objects for the first time.
The polychromatic polarization modulator
Show abstract
An increasing number of astronomical applications depend on the measurement of polarized light. For example, our
knowledge of solar magnetism relies heavily on our ability to measure and interpret polarization signatures introduced
by magnetic field. Many new instruments have consequently focused considerable attention on polarimetry. For solar
applications, spectro-polarimeters in particular are often designed to observe the solar atmosphere in multiple spectral
lines simultaneously, thus requiring that the polarization modulator employed is efficient at all wavelengths of interest. We
present designs of polarization modulators that exhibit near-optimal modulation characteristics over broad spectral ranges.
Our design process employs a computer code to optimize the efficiency of the modulator at specified wavelengths. We
will present several examples of modulator designs based on rotating stacks of Quartz waveplates and Ferroelectric Liquid
Crystals (FLCs). An FLC-based modulator of this design was recently deployed for the ProMag instrument at the Evans
Solar Facility of NSO/SP. We show that this modulator behaves according to its design.
The ZIMPOL high-contrast imaging polarimeter for SPHERE: design, manufacturing, and testing
Show abstract
ZIMPOL is the high contrast imaging polarimeter subsystem of the ESO SPHERE instrument. ZIMPOL is dedicated to
detect the very faint reflected and hence polarized visible light from extrasolar planets. ZIMPOL is located behind an
extreme AO system (SAXO) and a stellar coronagraph. SPHERE is foreseen to have first light at the VLT at the end of
2011. ZIMPOL is currently in the manufacturing, integration and testing phase. We describe the optical, polarimetric,
mechanical, thermal and electronic design as well as the design trade offs. Specifically emphasized is the optical quality
of the key performance component: the Ferro-electric Liquid Crystal polarization modulator (FLC). Furthermore, we
describe the ZIMPOL test setup and the first test results on the achieved polarimetric sensitivity and accuracy. These
results will give first indications for the expected overall high contrast system performance. SPHERE is an instrument
designed and built by a consortium consisting of LAOG, MPIA, LAM, LESIA, Fizeau, INAF, Observatoire de Genève,
ETH, NOVA, ONERA and ASTRON in collaboration with ESO.
Correcting polarization crosstalk in the ESPaDOnS spectro-polarimeter
Show abstract
ESPaDOnS is a high-resolution, cross-dispersed, fiber fed, echelle spectrograph in use at the Canada-France-Hawaii
Telescope (CFHT). The light from the telescope passes through a polarimeter stage before being injected into the fibers
that feed the spectrograph, so the instrument is capable of determining the polarization of the stellar spectra from 370 -
1000 nm in wavelength. One limit to the accuracy of the polarimetry is the inevitable polarization crosstalk added by all
optics prior to polarization analysis. The main source of this crosstalk is stress birefringence in the glass of the optics;
either residual from the annealing process or induced by the mounting of the optics. The process by which the crosstalk
in ESPaDOnS has been reduced from 5% or more to less than 1% is discussed in this paper.
Measurements and optimization of the occulting disk for the ASPIICS/PROBA-3 formation flying solar coronagraph
Show abstract
Solar coronagraphs in formation
ying require several mechanical and technological constraints to be met. One
of the most critical issues is the external occulter design and its optimization. The occulter edge requires special
attention in order to minimize the diraction while being compatible with the constraints of handling and
integrating large delicate space components. Moreover, it is practically impossible to realize a full scale model
for laboratory tests. This article describes the results of tests performed with a scaled-model breadboard of the
ASPIICS coronagraph disk edge, using the Articial Sun facility at Laboratoire d'Astrophysique de Marseille.
Utilization of redundant polarized solar spectra to infer the polarization properties of the new generation of large aperture solar telescopes
Show abstract
Spectro-polarimetry plays an important role in the study of solar magnetism and strongly influences the design of the
new generation of solar telescopes. Calibration of the polarization properties of the telescope is a critical requirement
needed to use these observations to infer solar magnetic fields. However, the large apertures of these new telescopes
make direct calibration with polarization calibration optics placed before all the telescope optical elements impractical.
It is therefore desirable to be able to infer the polarization properties of the telescope optical elements utilizing solar
observations themselves. Taking advantage of the fact that the un-polarized, linearly, and circularly polarized spectra
originating from the Sun are uncorrelated, we have developed techniques to utilize observations of solar spectra with
redundant combination of the polarization states measured at several different telescope configurations to infer the
polarization properties of the telescope as a whole and of its optical elements. We show results of these techniques
applied to spectro-plarimetric data obtained at the Dunn Solar Telescope.
The SALT HRS spectrograph: final design, instrument capabilities, and operational modes
Show abstract
The high-resolution échelle spectrograph, SALT HRS, is at an advanced stage of construction and will shortly become
available to the user community of the Southern African Large Telescope (SALT). This paper presents a commentary on
the construction progress to date and gives the instrument's final specification with refined estimates for its performance
based on the initial testing of the optics and the science-grade detectors. It also contributes a discussion of how the fibre
input optics have been tailored to specific scientific aspirations to give four distinct operational modes. Finally, the use of
the instrument is discussed in the context of the most common science cases.
Design of the CHIRON high-resolution spectrometer at CTIO
Show abstract
Small telescopes coupled to high resolution spectrometers are powerful tools for Doppler planet searches. They allow for
high cadence observations and flexible scheduling; yet there are few such facilities. We present an innovative and
inexpensive design for CHIRON, a high resolution (R~80.000) Echelle spectrometer for the 1.5m telescope at CTIO.
Performance and throughput are very good, over the whole spectral range from 410 to 870nm, with a peak efficiency of
15% in the iodine absorption region. The spectrograph will be fibre-fed, and use an iodine cell for wavelength
calibration. An image slicer permits a moderate beam size. We use commercially available, high performance optical
components, which is key for quick and efficient implementation. We discuss the optical design, opto-mechanical
tolerances and resulting image quality.
Overview of the GYES instrument: a multifibre high-resolution spectrograph for the prime focus of the Canada-France-Hawaii Telescope
Show abstract
ESA's cornerstone mission Gaia will construct a billion-star catalogue down to magnitude 20 but will only provide
detailed chemical information for the brighter stars and will be lacking radial velocity at the faint end due to
insufficient Signal-to-Noise Ratios (SNR). This calls for the deployment of a ground spectrograph under time
scales coherent with those of Gaia for a complementary survey.
The GYES instrument is a high resolution (~ 20,000) spectrometer proposed for installation on the Canada-
France-Hawaii Telescope (CFHT) to perform this survey in the northern hemisphere. It exploits the large Field
of View (FoV) available at the prime focus together with a high multiplex (~ 500 fibres) to achieve a SNR of 30
in two hours at magnitude 16 and render the survey possible on the order of 300 nights. The on-going feasibility
study aims at jointly optimising all components of the system: the field corrector, the positioner, the fibres
and the spectrograph. The key challenges consist in accommodating the components in the highly constrained
environment of the primary focus, as well as in achieving maximum efficiency thanks to high transmission
and minimum reconfiguration delays. Meanwhile, for GYES to have its first light at the time of Gaia's initial
data release (2014-2015), it is mandatory to keep its complexity down by designing a predominantly passive
instrument.
The optical design of a highly segmented, very wide-field spectrograph
Show abstract
In this paper we work out the optical design of, basically, a limited Field of View off-axis camera. This element is the
ingredient of a much more complex very wide field of view spectrograph and it is intended to avoid technological
difficulties related with huge optics by replicating such element (or family of such elements). The optical design has to
deal with the large off-axis aberration at a point in the Field of View as far from the optical axis as about 0.75 degree.
This requires special tools for treating the convergence of the optical design as, for instance, vignetting on the edges can
be severe because of the strong aberrations at the field lens entrance. Constraints into the optical design are particularly
interesting as well: in fact the overall cross section of the design have to lie within the footprint of the entrance Field of
View in order to allow for an array of such a design to be assembled together and guarantee the space for the allocation
of micro-mechanisms required for movable slits and grisms in each module.
Production-line assembly of 150+ VIRUS spectrographs
Show abstract
The Visual Integral-Field Replicable Unit Spectrograph (VIRUS) instrument is being built to support observations for
the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) project. The instrument consists of 150+ identical
fiber-fed integral field optical spectrographs. This instrument provides a unique challenge in astronomical
instrumentation: each of the 150+ instruments must be identical and each component must be interchangeable amongst
every other spectrograph in order to ease assembly and maintenance of the instrument. In this paper we describe plans
for the production-line assembly of the spectrographs. In particular, we discuss the assembly procedures and design
choices that will ensure uniformity of the spectrographs and support the project schedule.
A radial velocity spectrometer for the Automated Planet Finder Telescope at Lick Observatory
Show abstract
The Ken and Gloria Levy Spectrometer is being constructed at the Instrument Development Laboratory (Technical
Facilities) of UCO/ Lick Observatory for use on the 2.4 meter Automated Planet Finder Telescope at Mt. Hamilton. The
mechanical design of the instrument has been optimized for precision Doppler measurements. A key component of the
design is the space-frame structure that contains passive thermal compensation. Determinate hexapod structures are used
to mount the collimator, prism, and echelle grating. In this paper we describe the instrument mechanical design and some
features that will help it detect rocky planets in the habitable zone.
Mechanisms and instrument electronics for the Ohio State Multi-Object Spectrograph (OSMOS)
Show abstract
The Ohio State Multi-Object Spectrograph (OSMOS) is a new facility imager and spectrograph for the 2.4m
Hiltner telescope at the MDM Observatory. We present a detailed description of the mechanical and electronic
solutions employed in OSMOS, many of which have been developed and extensively tested in a large number
of instruments built at Ohio State over the past ten years. These solutions include robust aperture wheel and
linear stage designs, mechanism control with MicroLYNX programmable logic controllers, and WAGO fieldbus
I/O modules.
NEFER: a high-resolution scanning Fabry-Perot Spectrograph II scanning Fabry-Perot testing
Show abstract
NEFER (Nuevo Espectrómetro Fabry-Perot de Extrema Resolución) is a high spectral resolution, scanning Fabry-Perot
Spectrometer. It will be installed in the OSIRIS instrument at the GTC 10 m telescope. This 3D instrument uses a high
order scanning Fabry-Perot to obtain highly accurate kinematical information of extended cosmic sources such as
galaxies or nebulae. Astronomical data obtained with this instrument lead to a 3D spectroscopic data cubes composed of
several images, each one at different gaps of the scanning Fabry-Perot Interferometer. In this work we present laboratory
testing of some characteristics of the ICOS Fabry-Perot acquired for this instrument such Finesse, free spectral range,
and peak transmission. We also present software design and development for the 3D data reduction standalone package
of this high resolution 3D instrument.
First light results from PARAS: the PRL Echelle Spectrograph
Show abstract
We present the first light commissioning results from the Physical Research Laboratory (PRL) optical fiber-fed high
resolution cross-dispersed Echelle Spectrograph. It is capable of a single- shot spectral coverage of 3700A to 8600A at R
~ 63,000 and is under very stable conditions of temperature (0.04°C at 23°C). In the very near future pressure control
will also be achieved by enclosing the entire spectrograph in a low-pressure vacuum chamber (~0.01mbar). It is attached
to a 1.2m telescope using two 50micron core optical fibers (one for the star and another for simultaneous Th-Ar spectral
calibration). The 1.2m telescope is located at Mt. Abu, India, and we are guaranteed about 80 to 100 nights a year for
observations with the spectrograph. The instrument will be ultimately used for radial-velocity searches of exoplanets
around 1000 dwarf stars, brighter than 10th magnitude, for the next 5 years with a precision of 3 to 5m/s using the
simultaneous Th-Ar spectral lamp reference technique. The spectrograph has already achieved a stability of 3.7m/s in
short-term time scale and in the near future we expect the stability to be at 1m/s once we install the spectrograph inside
the vacuum chamber.
Astro-comb calibration of an Echelle Spectrograph
Show abstract
We describe recent work calibrating a cross-dispersed spectrograph with an "astro-comb" i.e., a high repetition rate,
octave spanning femtosecond laser frequency comb; and a filter cavity suppressing laser modes to match the resolution
of the spectrograph. Our astro-comb provides ~1500 evenly spaced (~0.6 A) calibration lines of roughly 100 nW per line
between 7800 and 8800 Angstroms. The calibration lines of the laser are stabilized to atomic clocks which can be
referenced to GPS providing intrinsic stability of the source laser below 1 cm/s in stellar radial velocity sensitivity, as
well as long term stability and reproducibility over years. We present calibration of the TRES spectrograph at the 1.5 m
telescope at the Fred L Whipple Observatory below 1 m/s radial velocity sensitivity in six orders from 7800-8800 A.
Analyzing the MUSE opto-mechanics serving as an optical bench in 3D space
Show abstract
The Multi Unit Spectroscopic Explorer MUSE is a second-generation VLT instrument. With its high multiplexing factor
of twenty-four individual spectrographs, it requires rather complex opto-mechanics to split the field of 1x1 arcminute on
the sky into twenty-four sub-fields and guide them along the central instrument structure to the feeding point of each
spectrograph. The requirements on the underlying mechanical structure are quite demanding in terms of opto-mechanical
stability under thermal loads and thermal mismatch, warping of its basement and excessive earthquake loads. In total
seven individual load cases and combinations of them have been analyzed in extensive finite-element analyses (within
Nastran) with subsequent optical analyses (within Zemax). These two types of analyses will be addressed here and their
combined output will be set into relation with the requirements.
Manufacturing and integration of the IFS integral spectrograph
Show abstract
Currently in the phase of the assembly, the Integral Field Spectrograph (IFS) is part of Sphere, which will see the first
light at ESO Paranal as a VLT second generation instruments in the 2011. In this paper we will describe the main aspects
in the Assembly, Integration and Testing phase (AIT) of the instrument at INAF-Osservatorio Astronomico di Padova
(OAPD) laboratory at the current stage. As result of the AIT, a full set of tests and qualifications of IFS subcomponents
will be discussed. These tests have been designed and realized with the purpose to obtain an accurate comparison
between design goals and effective performances of the instrument.
PUCHEROS: a low-cost fiber-fed Echelle Spectrograph for the visible spectral range
Show abstract
PUCHEROS is a high resolution optical Echelle spectrograph designed for the 50 cm telescope located at the
Pontificia Universidad Cat´olica de Chile (PUC) observatory of Santa Martina. With a resolution about 20,000,
PUCHEROS is an ideal instrument to study bright and variable objects, our driving science case is the study
of bright early type stars. Using a fiber optic to bring the light from the telescope to the instrument, it can be
located in a gravity invariant, temperature stabilized location, allowing precise long-term stability. PUCHEROS
will be a valuable tool both for research and didactics at the graduate and undergraduate level. In this work we
present the optical and mechanical design of the spectrograph as well as the first laboratory tests.
Design of Echelle Spectrograph for small telescopes with commercially available components
Show abstract
We present the design of an echelle spectrograph based on commercially available components. This instrument
is an ideal solution to equip small telescopes with low cost but scientifically effective instrumentation. The
spectrograph is fiber fed, reaches a resolution of about 8,000, can be located in a gravity invariant and thermally
controlled environment and can be used for the long term spectroscopic monitoring of bright objects. The optical
design and performances of the instrument are analyzed using Zemax, we present an option for the mechanical
design too.
A near-infrared spectrometer to measure zodiacal light absorption spectrum
Show abstract
We have developed a high throughput infrared spectrometer for zodiacal light Fraunhofer lines measurements. The instrument is based on a cryogenic dual silicon Fabry-Perot etalon which is designed to achieve high signal to noise Franuhofer line profile measurements. Very large aperture silicon Fabry-Perot etalons wand fast camera optics make these measurements possible. The results of the absorption line profile measurements will provide a model free measure of the zodiacal light intensity in the near infrared. The knowledge of the zodiacal light brightness is crucial for accurate subtraction of zodiacal light foreground for accurate measure of the extragalactic background light after the subtraction of zodiacal light foreground. We present the final design of the instrument and the first results of its performance.
Science capabilities of the Robert Stobie Spectrograph near infrared arm on SALT
Show abstract
The Robert Stobie Spectrograph Near Infrared Arm (RSS-NIR) is a new instrument on the 11-meter Southern African
Large Telescope (SALT), scheduled to begin commissioning in 2012. This versatile instrument will add capabilities that
are unique to large telescopes. The main instrument modes include NIR imaging, medium resolution long slit
spectroscopy over an 8 arcminute field of view (FOV), multi-object spectroscopy with custom slit masks over an 8x8
arcminute FOV, Fabry-Perot narrowband imaging over an 8 arcminute diameter FOV, and polarimetry and
spectropolarimetry over a 4x8 arcminute FOV. Limiting magnitude predictions are 21.1 and 20.1 for J and H band for
S/N = 10 per spectral resolution element in 1 hour for 1 arcsec2at an R=7000. All instrument modes can be operated
simultaneously with the RSS visible arm, providing spectral coverage from 0.32-1.7 microns. We list the science drivers
and describe the way in which they have guided the design for this instrument. We also present a more detailed
description of some several planned science programs that will take advantage of the unique capabilities of RSS-VISNIR
and the queue-scheduled SALT telescope. Lastly we give a brief description of predicted instrumental
performance, along with a comparison to several other NIR instruments at other observatories.
Design of the fiber optic support system and fiber bundle accelerated life test for VIRUS
Ian M. Soukup,
Joseph H. Beno,
Richard J. Hayes,
et al.
Show abstract
The quantity and length of optical fibers required for the Hobby-Eberly Telescope* Dark Energy eXperiment
(HETDEX) create unique fiber handling challenges. For HETDEX‡, at least 33,600 fibers will transmit light from the
focal surface of the telescope to an array of spectrographs making up the Visible Integral-Field Replicable Unit
Spectrograph (VIRUS). Up to 96 Integral Field Unit (IFU) bundles, each containing 448 fibers, hang suspended from the
telescope's moving tracker located more than 15 meters above the VIRUS instruments. A specialized mechanical system
is being developed to support fiber optic assemblies onboard the telescope. The discrete behavior of 448 fibers within a
conduit is also of primary concern. A life cycle test must be conducted to study fiber behavior and measure Focal Ratio
Degradation (FRD) as a function of time. This paper focuses on the technical requirements and design of the HETDEX
fiber optic support system, the electro-mechanical test apparatus for accelerated life testing of optical fiber assemblies.
Results generated from the test will be of great interest to designers of robotic fiber handling systems for major
telescopes. There is concern that friction, localized contact, entanglement, and excessive tension will be present within
each IFU conduit and contribute to FRD. The test apparatus design utilizes six linear actuators to replicate the movement
of the telescope over 65,000 accelerated cycles, simulating five years of actual operation.
A Fabry-Perot calibrator of the HARPS radial velocity spectrograph: performance report
Show abstract
The radial velocity (RV) technique has pushed the planet detection limits down to super-earths. To reach the
precision required to detect earth-like planets it is necessary to reach a precision around 1cm.s-1. Part of the error
budget is due to noise in the wavelength calibration of the spectrograph. The Observatory of Geneva has designed,
built and tested in collaboration with ESO a calibrator system based on a Fabry-Perot interferometer to explore its
potential to improve the wavelength calibration of RV spectrographs. We have obtained exciting results with the
calibrator system demonstrated 10 cm s-1 stability over one night. By further improving the injection system we are
aiming at a 1 m s-1 repeatability over the long term.
ESPRESSO: projecting a rocky exoplanet hunter for the VLT
Show abstract
ESPRESSO is a high-resolution, highly stable spectrograph for the VLT. It will inherit and enhance most capabilities
from HARPS and UVES, combining both stability and efficiency. The main science driver will be the detection and
characterization of Earth-like planets, but many additional science cases will benefit from its highly stable spectroscopic
observations. The facility will be installed at the combined Coudé focus of the VLT and may be linked with any of the
four UT telescopes, enabling thus a great flexibility for the efficient use of telescope time. This particularity makes the
interface with the VLT more complex than for an instrument fed by a single telescope. It impacts on the complexity of
the relationship between the consortium providing the instrument and ESO, the customer. The targeted high RV accuracy
requires very high performances in stability and resolution, which in turn require adequate technical solutions at several
levels. This paper describes the instrument system and subsystems, enlightening the most valuable differences between
ESPRESSO and it's predecessors, the details of the project, entering now the design phases, the ESPRESSO consortium,
composed of Italian, Portuguese, Spanish and Swiss institutes, and the relationship between the consortium and ESO.
KMOS pick-off arm optical alignment, calibration, and testing
Show abstract
The pick-off arm is the part of the KMOS instrument which re-images a sub-field of the VLT focal plane to a position
outside of the main field where it can be used for integral field spectroscopy. In this paper we describe the optical
alignment and test procedure developed to meet the challenging alignment requirements of the instrument. It is important
to note that although the alignment is done at ambient temperature, the alignment of the optical components must be
maintained at the instruments cryogenic operational temperature. This paper describes the methods used to achieve the
absolute positioning accuracy and the test results obtained and discussed some of the practical difficulties that were
encountered.
Development of the prototype integral field unit for prompt follow-up spectroscopy of gamma-ray bursts
Show abstract
We are now prototyping an integral field unit (IFU) using micro-lenses
and optical fibers for a new integral field spectrograph (IFS). The IFS is one of the primary instruments of a new 3.8m telescope which is under development. We report a basic concept of the IFS and current status of the prototyping work. One of main objectives of the 3.8m telescope is prompt follow-up spectroscopy of rapidly variable astronomical objects such as gamma-ray bursts (GRBs). The IFS allows us to omit procedures of target identification and acquisition, and to start exposure very quickly. We are developing a prototype IFU for the IFS in order to establish the construction techniques. We have already finished basic design, and moved to detailed design phase. We will install the prototype IFU into an existing optical imaging spectrograph of the 188cm telescope at Okayama Astrophysical Observatory for test observations. Through the test observations, we will establish the observing procedures and the data reduction techniques. The prototype IFU has the 20 x 20 arcsec^2 field of view (FoV) and the 2 arcsec spatial sampling on the 188cm telescope. The new IFS will have the 20 x 20 arcsec^2 FoV and the 1 arcsec spatial sampling on the 3.8m telescope. The X-ray telescope of the Swift satellite distributes GRB locations with a typical accuracy of 3-5 arcsec after 70 sec from GRB triggers. The FoV of the new IFS is much wider than this localization error circle and allows us to make prompt spectroscopy of GRBs.
KMOS: assembly, integration and testing of three 0.8-2.5 micron spectrographs
Show abstract
KMOS is a second generation instrument in construction for use at the European Southern Observatory (ESO)
Very Large Telescope (VLT). It operates in the near-infrared (0.8 to 2.5 microns) and employs 24 deployable,
image slicing integral field units (IFUs) feeding three spectrographs. The spectrographs are designed and built
by a partnership of the University of Oxford and Rutherford Appleton Laboratories (RAL). We describe the
assembly, integration and alignment procedures involved in the construction of these spectrographs in detail. We
also present the results of the cryogenic optical tests, including the first data taken through the full spectrograph
optical train and the details of the test facility and procedures involved.
The calibration unit and detector system tests for MUSE
Show abstract
The Multi-Unit Spectroscopic Explorer (MUSE) is an integral-field spectrograph for the ESO Very Large Telescope.
After completion of the Final Design Review in 2009, MUSE is now in its manufacture and assembly phase. To achieve
a relative large field-of-view with fine spatial sampling, MUSE features 24 identical spectrograph-detector units. The
acceptance tests of the detector sub-systems, the design and manufacture of the calibration unit and the development of
the Data Reduction Software for MUSE are under the responsibility of the AIP. The optical design of the spectrograph
implies strict tolerances on the alignment of the detector systems to minimize aberrations. As part of the acceptance
testing, all 24 detector systems, developed by ESO, are mounted to a MUSE reference spectrograph, which is illuminated
by a set of precision pinholes. Thus the best focus is determined and the image quality of the spectrograph-detector
subsystem across wavelength and field angle is measured.
The Carnegie Planet Finder Spectrograph: integration and commissioning
Show abstract
The Carnegie Planet Finder Spectrograph (PFS) has been commissioned for use with the 6.5 meter Magellan
Clay telescope at Las Campanas Observatory in Chile. PFS is optimized for high precision measurements of
stellar radial velocities to support an ongoing search for extrasolar planets. PFS uses an R4 echelle grating
and a prism cross-disperser in a Littrow arrangement to provide complete wavelength coverage between 388 and
668 nm distributed across 64 orders. The spectral resolution is 38,000 with a 1 arcsecond wide slit. An iodine
absorption cell is used to superimpose well-defined absorption features on the stellar spectra, providing a fiducial
wavelength reference. Several uncommon features have been implemented in the pursuit of increased velocity
stability. These include enclosing the echelle grating in a vacuum tank, actively controlling the temperature of
the instrument, providing a time delayed integration mode to improve flatfielding, and actively controlling the
telescope guiding and focus using an image of the target star on the slit. Data collected in the first five months
of scientific operation indicate that velocity precision better than 1 m s-1 RMS is being achieved.
Design of a near-IR Doppler instrument for planet searches
Show abstract
Doppler searches are extending to the near infrared to detect and characterize habitable planets around low mass stars.
We present an optical design and performance of a near-IR Doppler instrument. This instrument has two operating
modes covering 0.8-1.8 microns. One mode is called IRET, which consists of a fix-delay interferometer and a crossdispersed
echelle spectrograph to simultaneously cover 0.8-1.35 microns with a spectral resolution of R=22000 on a 2k x
2k H2RG IR array. The other mode is called FIRST, which uses a silicon immersion grating as the main disperser to
simultaneously cover 1.4-1.8 microns with a spectral resolution of R=55000 on the same detector as IRET. The triplepass
parabola white pupil design is used to restrain background scatter radiation with stable configuration for precision
radial velocity measurements. We used high index standard glasses for camera optics and VPH gratings as crossdispersers
in both modes. The FIRST mode can be switched in and out conveniently while the IRET mode is kept
without moving parts to increase its stability. This instrument is designed to deliver up to 1 m/s Doppler precision RV
measurements of nearby bright M dwarfs at the Apache Point Observatory 3.5 meter telescope. The instrument is
expected to be operational in the spring 2011.
Application of fixed delay Michelson interferometer for radial velocity measurement
Show abstract
Fixed Delay Michelson Interferometer (FDMI) also called Wide-Angle Michelson Interferometer (WAMI) is different
from conventional Michelson interferometer. Its fixed delay is not only useful to widen the field of view, but also
improve the accuracy of RV measurement. So it's widely known that works well on upper atmospheric wind study by
measuring the Doppler shift of single emission lines. On the other hand, a new technique called External Dispersed
Interferometry (EDI) can efficiently overcome the fundamental limitation of narrow bandpass of interferometer by
combination between FDMI and post-disperser. The related instruments have been successfully used in the exoplanet
exploration field. In this paper, the FDMI concept and its application in these two fields are reviewed, and a major
astronomical project in China, which is developing a multi-object exoplanet survey system (MESS) based on FDMI, is
introduced.
eXtreme multiplex spectrograph: a high-demanding mechanical design
Show abstract
XMS is a multi-channel wide-field spectrograph designed for the prime focus of the 3.5m Calar-Alto telescope. The
instrument is composed by four quadrants, each of which contains a spectrograph channel. An innovative mechanical
design -at concept/preliminary stage- has been implemented to: 1) Minimize the separation between the channels to
achieve maximal filling factor; 2) Cope with the very constraining space and mass overall requirements; 3) Achieve very
tight alignment tolerances; 4) Provide lens self-centering under large temperature excursions; 5) Provide masks including
4000 slits (edges thinner than 100μ). An overview of this very challenging mechanical design is here presented.
Time resolved astronomy with the SALT
Show abstract
While time resolved astronomical observations are not new, the extension of such studies to sub-second time resolution
is and has resulted in the opening of a new observational frontier, High Time Resolution Astronomy (HTRA). HTRA
studies are well suited to objects like compact binary stars (CVs and X-ray binaries) and pulsars, while asteroseismology
of pulsating stars, occultations, transits and the study of transients, will all benefit from such HTRA studies.
HTRA has been a SALT science driver from the outset and the first-light instruments, namely the UV-VIS imager,
SALTICAM, and the multi-purpose Robert Stobie Spectrograph (RSS), both have high time resolution modes. These are
described, together with some observational examples. We also discuss the commissioning observations with the photon
counting Berkeley Visible Image Tube camera (BVIT) on SALT. Finally we describe the software tools, developed in
Python, to reduce SALT time resolved observations.
A new MOS mask cutter facility at Gemini/Cerro Tololo observatories
Show abstract
The installation and commissioning of a new laser cutter facility in La Serena, Chile is a cooperative effort between Gemini Observatory and the Cerro Tololo Inter-American Observatory. This system enables the cutting of aluminum and carbon fiber slit masks for three multi-object spectrographs operating in Chile: GMOS-S, Flamingos-2, and Goodman spectrograph. Selection of the new laser cutter tool was based on slit mask specifications developed for two materials. Prior to the commissioning all slit mask production was performed at Gemini's Northern base facility with a similar laser cutter system. The new facility supports two observatories and enhances the capabilities for both. This paper will discuss the observatory arrangement with respect to mask data tracking and handling. The laser system and facility will be discussed along with mask cutting performance, process development and manufacturing methods.
The differential tip-tilt sensor of SPHERE
Show abstract
The SPHERE instrument aims at detecting giant extrasolar planets in the vicinity of bright stars. Such a challenging goal
requires the use of a high performance Adaptive Optics (AO) system, a coronagraphic device to cancel out the flux
coming from the star itself, and smart focal plane techniques to calibrate residual uncorrected turbulent and/or static
wavefronts. Inside the adaptive optic system, a specific tool is developed in SPHERE to ensure that the star is always
well centered on the coronagraph. This tool called Differential Tip-Tilt Sensor (DTTS) measures the position of the star
at the same wavelength than the science instruments. It is located very close to the focal plane to minimize drifts between
DTTS and the coronagraph. After describing the DTTS, we will describe the tests and laboratory results on stability
measurement of the DTTS; stability which is crucial for SPHERE performance.
Automated characterization of CCD detectors for DECam
Show abstract
The Dark Energy Survey Camera (DECam) will be comprised of a mosaic of 74 charge-coupled devices (CCDs). The
Dark Energy Survey (DES) science goals set stringent technical requirements for the CCDs. The CCDs are provided by
LBNL with valuable cold probe data at 233 K, providing an indication of which CCDs are more likely to pass. After
comprehensive testing at 173 K, about half of these qualify as science grade. Testing this large number of CCDs to
determine which best meet the DES requirements is a very time-consuming task. We have developed a multistage
testing program to automatically collect and analyze CCD test data. The test results are reviewed to select those CCDs
that best meet the technical specifications for charge transfer efficiency, linearity, full well capacity, quantum efficiency,
noise, dark current, cross talk, diffusion, and cosmetics.
Poster Session II
Science requirements and performances for EAGLE for the E-ELT
Show abstract
EAGLE is a Phase A study of a multi-IFU, near-IR spectrometer for the European Extremely Large Telescope (E-ELT).
The design employs wide-field adaptive optics to deliver excellent image quality across a large (38.5 arcmin2) field.
When combined with the light grasp of the E-ELT, EAGLE will be a unique and efficient facility for spatially-resolved,
spectroscopic surveys of high-redshift galaxies and resolved stellar populations. Following a brief overview of the
science case, here we summarise the functional and performance requirements that flow-down from it, provide
illustrative performances from simulated observations, and highlight the strong synergies with the James Webb Space
Telescope (JWST) and the Atacama Large Millimeter Array (ALMA).
Mid-infrared astronomy with the E-ELT: performance of METIS
Show abstract
We present results of performance modelling for METIS, the Mid-infrared European Extremely Large Telescope
Imager and Spectrograph. Designed by a consortium of NOVA (Netherlands), UK Astronomy Technology Centre
(UK), MPIA Heidelberg (Germany), CEA Saclay (France) and KU Leuven (Belgium), METIS will cover the
atmospheric windows in L, M and N-band and will offer imaging, medium-resolution slit spectroscopy (R~1000-
3000) and high-resolution integral field spectroscopy (R~100,000). Our model uses a detailed set of input
parameters for site characteristics and atmospheric profiles, optical design, thermal background and the most
up-to-date IR detector specifications. We show that METIS will bring an orders-of-magnitude level improvement
in sensitivity and resolution over current ground-based IR facilities, bringing mid-IR sensitivities to the micro-
Jansky regime. As the only proposed E-ELT instrument to cover this entire spectral region, and the only mid-IR
high-resolution integral field unit planned on the ground or in space, METIS will open up a huge discovery space
in IR astronomy in the next decade.
MICADO: optical configuration, performance, and folding
Show abstract
MICADO will be the IR imaging camera for the E-ELT. It has been designed to work in conjunction with both SCAO
(in the early phase) and LGS-MCAO system MAORY (for which it has been optimized) and delivers diffraction limited
quality over about 1 arcmin field of view covering the wavelength range from 0.8 to 2.5 micron. In this paper, we
describe the optical configurations and the observing modes, for both the primary and the auxiliary arms, of the current
baseline and we show the expected performances and how the optical path can be folded to fit the available limited space
in the cryo-chamber.
Expected performance and simulated observations of the instrument HARMONI at the European Extremely Large Telescope (E-ELT)
Show abstract
HARMONI has been conceived as a workhorse visible and near-infrared (0.47-2.45 microns) integral field spectrograph
for the European Extremely Large Telescope (E-ELT). It provides both seeing and diffraction limited observations at
several spectral resolutions (R= 4000, 10000, 20000). HARMONI can operate with almost any flavor of AO (e.g.
GLAO, LTAO, SCAO), and it is equipped with four spaxel scales (4, 10, 20 and 40 mas) thanks to which it can be
optimally configured for a wide variety of science programs, from ultra-sensitive observations of point sources to highangular
resolution spatially resolved studies of extended objects. In this paper we describe the expected performance of
the instrument as well as its scientific potential. We show some simulated observations for a selected science program,
and compare HARMONI with other ground and space based facilities, like VLT, ALMA, and JWST, commenting on
their synergies and complementarities.
CODEX optics
Show abstract
CODEX is a high resolution spectrograph for the ESO E-ELT. A classical spectrograph can only achieve a resolution of
about 120.000 on a 42 m telescope with extremely large echelle gratings and cameras. This paper describes in detail the
optical concept of CODEX, which uses only optical elements size similar to those in current high resolution
spectrographs. This design is based on slicers, anamorphic beams and slanted VPHG as cross dispersers. In this new
version of the CODEX design, no special expensive materials as calcium fluoride or abnormal dispersion glasses are
needed. The optical quality is excellent and compatible with 10K x 10K detectors with 10 μm pixels.
Web-based scientific simulation tools for E-ELT instruments
Show abstract
In the frame of the EAGLE phase A study, we have developed a scientific simulator which has been used to constrain the instrument high level specifications. This simulator was coupled to a web interface to allow an easier access by the EAGLE science team, and run specific simulations covering the EAGLE scientific objectives. We give a functional description of this simulator, and illustrate how it was used in practice to derive a specification on the Ensquared Energy of EAGLE. Given the success of the EAGLE simulator, we developed other telescope/instrument simulators, including a general image/datacube simulator which is now freely accessible on the web.
OPTIMOS-EVE design trade-off analysis
Show abstract
OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fiber fed multi object
spectrograph proposed for the E-ELT. It is designed to provide a spectral resolution ranging from 5000 to 30.000, at
wavelengths from 0.37 μm to 1.70 μm, combined with a high multiplex (>200) and a large spectral coverage. The
system consists of three main modules: a fiber positioning system, fibers and a spectrograph.
The OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT instrumentation studies, has
been performed by an international consortium consisting of institutes from France, Netherlands, United Kingdom, Italy
and Denmark.
This paper describes the design tradeoff study and the key issues determining the price and performance of the
instrument.
The Infrared Imaging Spectrograph (IRIS) for TMT: the science case
Show abstract
The InfraRed Imaging Spectrograph (IRIS) is a first-light instrument being designed for the Thirty Meter Telescope
(TMT). IRIS is a combination of an imager that will cover a 16.
4 field of view at the diffraction limit of
TMT (4 mas sampling), and an integral field unit spectrograph that will sample objects at 4-50 mas scales. IRIS
will open up new areas of observational parameter space, allowing major progress in diverse fields of astronomy.
We present the science case and resulting requirements for the performance of IRIS. Ultimately, the spectrograph
will enable very well-resolved and sensitive studies of the kinematics and internal chemical abundances of
high-redshift galaxies, shedding light on many scenarios for the evolution of galaxies at early times. With unprecedented
imaging and spectroscopy of exoplanets, IRIS will allow detailed exploration of a range of planetary
systems that are inaccessible with current technology. By revealing details about resolved stellar populations
in nearby galaxies, it will directly probe the formation of systems like our own Milky Way. Because it will be
possible to directly characterize the stellar initial mass function in many environments and in galaxies outside
of the the Milky Way, IRIS will enable a greater understanding of whether stars form differently in diverse
conditions. IRIS will reveal detailed kinematics in the centers of low-mass galaxies, allowing a test of black hole
formation scenarios. Finally, it will revolutionize the characterization of reionization and the first galaxies to
form in the universe.
The science calibration system for the TMT NFIRAOS and client instruments: requirements and design studies
Show abstract
We present the results of the design studies of the science calibration system for the adaptive optics and infrared
instruments of the Thirty Meter Telescope. The two major requirements of the science calibration system are to provide
pupil-simulated telescope beams to the adaptive optics system for calibration of the telescope pupil and to provide flatfielding
and wavelength-calibration illuminations to client instruments of the adaptive optics system. Our current system
is composed an integrating sphere with calibration light sources, a retractable pupil-mask system, a lens assembly
consisting of a pair of achromatic triplets, and fold mirrors. This system appears to be capable of producing highlyuniform
of f/15 beams at the telescope focal plane and pupil simulation at a pupil location within the adaptive optics
system. We describe the present design and development of the calibration system along with relevant analyses.
The science drivers for a mid-infrared instrument for the TMT
Show abstract
A mid-infrared (MIR) imager and spectrometer is being investigated for possible consideration for construction
in the early operation of the Thirty Meter Telescope (TMT). Combined with adaptive optics for the MIR, the
instrument will afford 15 times higher sensitivity (0.1mJy as 5 sigma detection in 1hour integration in the N-band
imaging) and 4 times better spatial resolution (0.08") at 10μm compared to 8m-class telescopes. In addition, its
large light-gathering power allows high-dispersion spectroscopy in the MIR that will be unrivaled by any other
facility. We, a collaborating team of Japanese and US MIR astronomers, have carefully considered the science
drivers for the TMT MIR instrument. Such an instrument would offer both broad and potentially transformative
science. Furthering the science cases for the MIRES1, where high-dispersion spectroscopy was emphasized, we
discuss additional capabilities for the instrument drawn from the enlarged science cases. The science cases include
broader areas of astronomical fields: star and planet formation, solar system bodies, evolved stars, interstellar
medium (ISM), extragalaxies, and cosmology. Based on these science drivers, essential instrument capabilities
and key enhancement are discussed (see the companion paper Tokunaga et al. 20102): specifically imaging, lowand
high-spectral resolution modes, integral field spectroscopy, and polarimetry.
An Infrared Multi-Object Spectrograph (IRMS) with adaptive optics for TMT: the science case
Show abstract
It has been recognized that a Near-Infrared Multi-object Spectrograph (IRMS)
as one of the first light instrument on the Thirty Meter Telescope (TMT) would significantly
increase the scientific capability of the observatory. The IRMS is planned to be a clone of the
MOSFIRE instrument on the Keck telescope. As a result, we use the already available MOSFIRE
design and expertise, significantly reducing the total cost and its development time. The IRMS will
be a quasi diffraction limited multi-slit spectrograph with moderate resolution (R~4000), fed by
Narrow-Field Infrared Adaptive Optics System (NFIRAOS). It images over the 2 arcmin diameter
field of view of the NFIRAOS.
There are a number of exceedingly important scientific questions, waiting to be addressed by the
TMT/IRMS combination. Given its relatively small field of view, it is less affected by the sky
background, which is a limiting factor in ground-based observations at near-IR wavelengths. The
IRMS is the ideal instrument for studying spectroscopic properties of galaxies at the re-ionization
epoch (z > 7), where the Lyman alpha line shifts to the near-ir wavelenghths. It can be used to
measure rotation curves of spiral and velocity dispersion of elliptical galaxies at z~2-3 and hence,
their spectroscopic mass. It can be used to search for population III stars via their spectroscopic
signature and to perform measurement of spectroscopic lines at high redshifts, diagnostic of
metallicity. Finally, IRMS allows measurement of the blue shifts in the rest-frame MgII line for
high redshift
galaxies, used to study the winds, leading to the feedback mechanism, responsible for quenching
star formation activity in galaxies.
The Infrared Imaging Spectrograph (IRIS) for TMT: the atmospheric dispersion corrector
Show abstract
We present a conceptual design for the atmospheric dispersion corrector (ADC) for TMT's Infrared Imaging
Spectrograph (IRIS). The severe requirements of this ADC are reviewed, as are limitations to observing caused by
uncorrectable atmospheric effects. The requirement of residual dispersion less than 1 milliarcsecond can be met with
certain glass combinations. The design decisions are discussed and the performance of the design ADC is described.
Alternative options and their performance tradeoffs are also presented.
Science flow down for the Thirty Meter Telescope
Show abstract
How do we know that the current technical requirements and architecture for the Thirty-Meter Telescope Observatory
will indeed allow TMT to tackle the broad range science within the reach of a large optical/IR telescope and fully realize
its scientific potential? The path from science to observatory design is frequently not linear and often involves multiple
iterations. Ideally, the final design will meet as many science requirements as possible within the constraints imposed by
technological readiness, schedule and cost. A properly established science flowdown plays an invaluable role in
estimating the impact of various design decisions (including instrument selection) on science returns. In this paper, we
describe the flowdown of scientific and observatory requirements from the TMT science cases in terms of the following
key elements: the science programs themselves, the science flowdown matrix, the Science-based Requirements
Documents (SRD), the Observatory Requirements, the Observatory Architecture and the Operations Concepts
Documents (ORD, OAD and OCD).
The Infrared Imaging Spectrograph (IRIS) for TMT: imager design
Show abstract
We describe an optical design of an imager mode of the IRIS instrument for the Thirty Meter Telescope. IRIS
is a fully-cryogenic diffraction-limited infrared camera and integral field spectrograph working in the wavelength
coverage from 0.84 to 2.4 microns. The imager mode covers 16.4" × 16.4" FOV with a 4096 × 4096 detector
array with sampling 4 milli-arcsec/pix. There are two challenges in performance which the science cases require
in the imager mode. 1) rms wavefront error should be less than 30 nm, and 2) optical distortion should be
corrected sufficiently to achieve astrometric accuracy of 10 micro-arcsec. Among possible optical configurations
consisting of reflective and refractive solutions, a refractive solution with apochromatic triplets best meets the
requirements. The optical system consists of a collimator and camera both of which have a BaF2-Fused Silica-
ZnSe apochromatic triplet and a single BaF2 lens near the focus. The rms wavefront error of the system including
the telescope, adaptive optics, and imager mode is less than 22 nm with ideal optical parameters. A sensitivity
analysis shows that reasonable amount of errors in fabrication and alignment will give the rms wavefront error of
less than 30 nm in 90 % of all cases. We also investigate accuracy of the distortion correction and how movable
parts affect the correction accuracy. We find that uncorrectable distortion correction errors are well below 10
micro-arcsec with reasonable stability and repeatability of the movable parts.
Conceptual design phase stray light analysis of the MOBIE imaging spectrograph for TMT
Show abstract
The Multi-Object Broadband Imaging Echellette (MOBIE) is the seeing-limited, optical spectrograph planned for the
first generation of Thirty Meter Telescope (TMT) instruments1. An end-to-end stray light analysis of the full optical path
(telescope to detector array) has been undertaken as a first step towards validating the design concept with regard to stray
light requirements. The geometric, stray light model includes the TMT Calotte-style dome structure, telescope optics,
telescope support structures, and the MOBIE instrument itself. The stray light calculations, including assumptions,
methodology, and conclusions, are described. Particular emphasis is placed on the stray light contributions from the
telescope, atmospheric dispersion corrector, and spectrograph optics. Recommendations for stray light controls internal
to the MOBIE instrument are discussed.
Instrumentation at Paranal Observatory: maintaining the instrument suite of five large telescopes and its interferometer alive
Show abstract
This presentation provides interesting miscellaneous information regarding the instrumentation activities at Paranal
Observatory. It introduces the suite of 23 instruments and auxiliary systems that are under the responsibility of the
Paranal Instrumentation group, information on the type of instruments, their usage and downtime statistics. The data is
based on comprehensive data recorded in the Paranal Night Log System and the Paranal Problem Reporting System
whose principles are explained as well. The work organization of the 15 team members around the high number of
instruments is laid out, which includes:
- Maintaining older instruments with obsolete components
- Receiving new instruments and supporting their integration and commissioning
- Contributing to future instruments in their developing phase.
The assignments of the Instrumentation staff to the actual instruments as well as auxiliary equipment (Laser Guide Star
Facility, Mask Manufacturing Unit, Cloud Observation Tool) are explained with respect to responsibility and scheduling
issues. The essential activities regarding hardware & software are presented, as well as the technical and organizational
developments within the group towards its present and future challenges.
Nasmyth focus instrumentation of the New Solar Telescope at Big Bear Solar Observatory
Show abstract
The largest solar telescope, the 1.6-m New Solar Telescope (NST) has been installed and is being commissioned
at Big Bear Solar Observatory (BBSO). It has an off-axis Gregorian configuration with a focal ratio of F/52.
Early in 2009, first light scientific observations were successfully made at the Nasmyth focus, which is located
on the east side of the telescope structure. As the first available scientific instruments for routine observation,
Nasmyth focus instrumentation (NFI) consists of several filtergraphs offering high spatial resolution photometry
in G-band 430 nm, Ha 656 nm, TiO 706 nm, and covering the near infrared 1083 nm, 1.6 μm, and 2.2 μm. With
the assistance of a local correlation tracker system, diffraction limited images were obtained frequently over a
field-of-view of 70 by 70 after processed using a post-facto speckle reconstruction algorithm. These data sets not
only serve for scientific analysis with an unprecedented spatial resolution, but also provide engineering feedback
to the NST operation, maintenance and optimization. This paper reports on the design and the implementation
of NFI in detail. First light scientific observations are presented and discussed.
SOFIA image motion compensation
Show abstract
We describe a laboratory simulation of an image motion compensation system for SOFIA that uses high-speed image
acquisition from the science instrument HIPO as the sensing element of the system and a Newport voice-coil actuated
fast steering mirror as the correcting actuator. Performance of the system when coupled to the SOFIA secondary mirror
is estimated based on the known current performance of the secondary mirror controller. The system is described and
the observed performance is presented together with expectations for applicability in flight with SOFIA.
Data reduction strategies for lucky imaging
Show abstract
Lucky imaging is a proven technique for near diffraction limited imaging in the visible; however, data reduction
and analysis techniques are relatively unexplored in the literature. In this paper we use both simulated and real
data to test and calibrate improved guide star registration methods and noise reduction techniques. In doing
so we have produced a set of "best practice" recommendations. We show a predicted relative increase in Strehl
ratio of ~ 50% compared to previous methods when using faint guide stars of ~17th magnitude in I band, and
demonstrate an increase of 33% in a real data test case. We also demonstrate excellent signal to noise in real
data at flux rates less than 0.01 photons per pixel per frame above the background flux level.
Broad band imager for the European Solar Telescope
Show abstract
The European Solar Telescope (EST) is a joint project of several European research institutes to design and realize a 4-m
class solar telescope. The EST broad band imager is an imaging instrument whose function is to obtain diffraction
limited images over the full field of view of EST at multiple wavelengths and high frame rate. Its scientific objective is
the study of fundamental astrophysical processes at their intrinsic scales in the Sun's atmosphere. The current layout
foresee two observation modes: a maximum field of view mode and a high resolution mode. The imager will have a 2'x2'
corrected field of view in the first mode and an angular resolution better than 0.04" at 500nm in the latter mode. The
imager will cover a wavelength range spanning from 390nm to 900nm through a number of filters with bandpasses
between 0.05nm and 0.5nm. To optimize optical performances and throughput there will be two arms working
simultaneously: a blue arm (covering the 380nm - 500nm range) and a red arm (600nm - 900nm). The blue arm will
have two channels while the red arm only one. Each channel will be divided in three subchannels: one will host narrow
band filters for chromospheric observations, another one, in focus wide band filters used as reference for speckle
reconstruction and photospheric observations, and the last one, out of focus wide band filters for phase diversity
reconstruction of photospheric observations.
MiniTAO/MAX38 first light: 30-micron band observations from the ground-based telescope
Show abstract
We successfully carried out 30-micron observations from the ground-based telescope for the first time with our newly
developed mid-infrared instrument, MAX38, which is mounted on the University of Tokyo Atacama 1.0-m telescope
(miniTAO telescope). Thanks to the high altitude of the miniTAO (5,640m) and dry weather condition of the Atacama
site, we can access the 30-micron wavelength region from ground-based telescopes. To achieve the observation at 30-
micron wavelength, remarkable devices are employed in MAX38. First, a Si:Sb 128x128 array detector is installed
which can detect long mid-infrared light up to 38-micron. Second, we developed metal mesh filters for 30-micron region
band-pass filter, which are composed of several gold thin-films with cross-shaped holes. Third, a cold chopper, a 6-cm
square plane mirror controlled by a piezoelectric actuator, is built into the MAX38 optics for canceling out the
atmospheric turbulence noise. It enables square-wave chopping with a 50-arcsecound throw at a frequency more than 5-
Hz. Finally, a low-dispersion grism spectrometer (R~50) will provide information on the transmission spectrum of the
terrestrial atmosphere in 20 to 40 micron. In this observation, we clearly demonstrated that the atmospheric windows
around 30-micron can be used for the astronomical observations at the miniTAO site.
Fast photometry mode possibilities for the Canarias Infrared Camera Experiment (CIRCE)
Show abstract
In this paper we analyze different solutions to implement a fast photometry mode in the Canarias InfraRed Camera
Experiment (CIRCE), a visitor-class near-IR imager, spectrograph, and polarimeter for the 10.4 meter Gran Telescopio
Canarias (GTC). The fast photometry mode will be one of the enhanced capabilities of CIRCE that will differentiate our
instrument from similar instruments. The fast photometry capability, along with the polarimetric and spectroscopic
capabilities of the instrument will provide a unique instrument for the study of rapidly-varying objects. We combine the
different output modes of the HAWAII-2 2048x2048 detector, with very simple modifications in our already built Array
Controller Subsystem (MCE-3), and with modifications in the firmware of the readout control electronics to provide the
instrument with this powerful capability. We expect to increase the frame capture rate on the order of 5 to 14 times faster
depending on the frame size and the final solutions chosen.
Two-degree FOV prime focus corrector and ADC concepts for the 4.2m WHT
Show abstract
We present two conceptual optical designs for a new refractive corrector for the prime focus of the 4.2m William
Herschel Telescope, optimised to allow wide-field multi-object spectroscopy. The proposed designs satisfy the
demanding requirement that the PSF be smaller than 0.5 arcsec (80% encircled energy) over a two degree FOV and a
wavelength range of 370 - 1000 nm. We discuss the specifications and describe the design process for the correctors,
which also act as atmospheric dispersion correctors (ADC). The designs we present form the basis of a realistic
manufacturable system.
Spectrophotometric calibration system for DECam
Show abstract
We present a spectrophotometric calibration system that will be implemented as part of the DES DECam project at the
Blanco 4 meter at CTIO. Our calibration system uses a 2nm wide tunable source to measure the instrumental response
function of the telescope from 300nm up to 1100nm. The system consists of a monochromator based tunable light source
that is projected uniformly on a Lambertian screen using a broadband "line to spot" fiber bundle and an engineered
diffuser. Several calibrated photodiodes strategically positioned along the beam path will allow us to measure the
throughput as a function of wavelength. Our system has an output power of 0.25 mW, equivalent to a flux of
approximately 100 photons/s/pixel on DECam. We also present results from the deployment of a prototype of this
system at the Swope 1m at Las Campanas Observatory for the calibration of the photometric equipment used in the
Carnegie Supernova Project.
Improved REM telescope interface with a new simultaneous multiband visible camera
Show abstract
A new mechanical interface between the telescope Nasmyth derotator and the focal plane instrumentation has been
developed and built for the robotic REM telescope in La Silla. A light-weighted flange will substitute the existing one in
order to improve performances in term of mechanical flexures. A new ghost-free, high performances, dichroic has been
designed and installed inside the new mechanical flange, improving the efficiency of the wavelength splitting between
the visible and the near-infrared channels. The visible camera has been completely redesigned in order to get
simultaneous multi-band coverage within the existing 10'x10' field of view. Four bands will be observed onto the same
2kx2k, 13.5 micron pixel, detector. Band splitting is obtained with plate dichroics, working at 45 deg of incidence angle.
It will allow to fast observe gamma-ray burst afterglow from the 400 nm up to 2.5 micron, to better characterize spectral
features of these fastly evolving sources.
Self-coherent camera: first results of a high-contrast imaging bench in visible light
Show abstract
Extreme adaptive optics and coronagraphy are mandatory for direct imaging of exoplanets. Quasi-static aberrations
limit the instrument performance producing speckle noise in the focal plane. We propose a Self-Coherent
Camera (SCC) to both control a deformable mirror that actively compensates wavefront error, and calibrate the
speckle noise. We create a reference beam to spatially modulate the coronagraphic speckle pattern with Fizeau
fringes. In a first step, we are able to extract wavefront aberrations from the science image and correct for them
using a deformable mirror. In a second step, we apply a post-processing algorithm to discriminate the companion
image from the residual speckle field.
To validate the instrumental concept, we developed a high contrast imaging bench in visible light. We associated
a SCC to a four quadrant phase mask coronagraph and a deformable mirror (DM) with a high number
of actuators (32x32 Boston Michromachines MEMS). We will present this bench and show first experimental
results of focal plane wavefront sensing and high contrast imaging. The measurements are compared to numerical
simulations.
A high-efficiency fibre double-scrambler prototype
Show abstract
Results for a high efficiency fibre double-scrambler are reported. The scrambler is based on the concept first
presented by Casse and Vieira (1997) but with a substantial improvement in performance. The design uses a
simple finite conjugate relay with large magnification followed by a combined scrambler/focal reducer singlet.
This approach allows flexibility in the coupling of fibres with various focal ratios and diameters, and can be used
to minimize loss of throughput due to focal ratio degradation. A prototype has been constructed using simple
off-the-shelf optics which is shown to be capable of coupling a 15m long 300 μm fibre to a 5m long 320 μm fibre
with an absolute efficiency of 75%. The focal ratio degradation (FRD) of the prototype is 7% when operated at
f/3.65. A fully optimized version with both improved efficiency (>85%) and FRD is intended to be deployed as
part of the Hobby Eberly Telescope HRS upgrade.
MANIFEST: a many-instrument fiber-positioning system for GMT
Show abstract
MANIFEST (the Many Instrument Fiber System) is a proposed fiber-positioner for the GMT, capable of feeding other
instruments as needed. It is a simple, flexible and modular design, based on the AAO's Starbugs, the University of
Sydney's Hexabundles, and extensive use of standard telecommunications fiber technology. Up to 2000 individually
deployable fiber units are envisaged, with a wide variety of aperture types (single-aperture, image-slicing, IFU).
MANIFEST allows (a) full use of the GMT's 20' field-of-view, (b) a multiplexed IFU capability, (c) greatly increased
spectral resolution via image-slicing, (d) efficient detector packing both spectrally and spatially, (e) the possibility of
OH-suppression in the near-infrared. Together, these gains make GMT the most powerful of the ELT's for wide-field
spectroscopy. It is intended that MANIFEST will form part of the GMT facility itself, available to any instrument able
to make use of it.
APOGEE cryostat design
Show abstract
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a survey of all Galactic stellar populations
that will employ an R=30,000 spectrograph operating in the near-infrared (1.5-1.7μm) wavelength range. The fiber-fed
spectrograph is housed in a large (1.4m x 2.3m x 1.3m) stainless steel cryostat or Dewar that is LN2-cooled and will be
located in a building near the 2.5m Sloan Digital Sky Survey (SDSS) telescope to which it will be coupled. The choice
of shell material and configuration was an optimization among optics packaging, weight, strength, external dimensions,
rigging and transportation, the available integration and testing room, and the ultimate instrument room at APO.
Internals are fabricated of more traditional 6061-T6 aluminum which is well proven in cryogenic applications. An active
thermal shield with MLI blanketing yields an extremely low thermal load of 45-50 watts for this ~3000 liter instrument.
Cryostat design details are discussed with applicable constraints and trade decisions. APOGEE is one of four
experiments that are part of Sloan Digital Sky Survey III (SDSS-III).
APOGEE fiber development and FRD testing
Show abstract
Development of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) near-infrared spectrograph
has motivated thorough investigation into the properties and performance of optical fibers. The fiber selected for
APOGEE is a step index, multi-mode fiber, developed by PolyMicro, with a 120μm low OH, fused silica core, 25μm
cladding, and 10μm buffer. The instrument design includes a 40 meter fiber run, connecting the spectrograph to the
2.5m Sloan Digital Sky Survey (SDSS) telescope, and an additional 2.5 meter fiber segment located within the
instrument dewar, a vacuum-sealed, cryogenic environment. This light path is convoluted and includes many transitions
and connections where the beam is susceptible irrevocable loss. To optimize the spectrograph performance it is
necessary to minimize the losses incurred in the fiber system, especially those resulting in focal ratio degradation (FRD).
The focus of this research has been to identify potential sources of loss and where applicable, select material components
to minimize this effect. There is little previous documented work concerning the performance of optical fibers within
this wavelength band (1.5-1.7μm). Consequently, the following includes comprehensive explanations of the APOGEE
fiber system components, our experimental design and optical test bed set-up, beam alignment procedures, fiber
terminating and polishing techniques, and results from our examination of FRD as correlated with source wavelength,
fiber length and termination, and environmental conditions.
Multiband filters for near-infrared astronomical applications
Show abstract
Filters for astronomical imaging traditionally have a simple bandpass that admits (more or less equally) all the
photons within some bandwith ▵λ around some central wavelength λ0. However, there are situations where
not all photons are equally desirable. We plan to develop and apply multiband filters for practical astronomical
application. A multiband filter is a bandpass filter whose transmission dips to zero at select, undesired wavelength
ranges. Anticipated applications include (i) OH-suppressing filters, especially in the J band (λc ≈ 1.2μm); (ii)
economy of filter slots through multi-band filters used in series with broad blocking filters; and (iii) efficient
searches for object classes with highly structured spectra. We present the design and anticipated photometric
properties of a prototype reduced-background JR filter, which we plan to buy and test in 2010.
Design and implementation of an improved chilled water glycol system for GeMS: CANOPUS thermal enclosures
Show abstract
CANOPUS is the facility instrument for the Gemini Multi Conjugate Adaptive Optics System (GeMS) wherein all the
adaptive optics mechanisms and associated electronic are tightly packed. At an early stage in the pre-commissioning
phase Gemini undertook the redesign and implementation of its chilled Ethylene Glycol Water (EGW) cooling system to
remove the heat generated by the electronic hardware. The electronic boards associated with the Deformable Mirrors
(DM) represent the highest density heat yielding components in CANOPUS and they are also quite sensitive to
overheating. The limited size of the two electronic thermal enclosures (TE) requires the use of highly efficient heat
exchangers (HX) coupled with powerful yet compact DC fans.
A systematic approach to comply with all the various design requirements brought about a thorough and robust solution
that, in addition to the core elements (HXs and fan), makes use of features such as high performance vacuum insulated
panels, vibration mitigation elements and several environment sensors. This paper describes the design and
implementation of the solution in the lab prior to delivering CANOPUS for commissioning.
DMD-based MOS demonstrator on Galileo Telescope
Show abstract
Multi-Object Spectrographs (MOS) are the major instruments for studying primary galaxies and remote and faint
objects. Current object selection systems are limited and/or difficult to implement in next generation MOS for space and
ground-based telescopes. A promising solution is the use of MOEMS devices such as micromirror arrays which allow
the remote control of the multi-slit configuration in real time.
We are developing a Digital Micromirror Device (DMD) - based spectrograph demonstrator. We want to access the
largest FOV with the highest contrast. The selected component is a DMD chip from Texas Instruments in 2048 x 1080
mirrors format, with a pitch of 13.68μm. Such component has been also studied by our team for application in
EUCLID-NIS. Our optical design is an all-reflective spectrograph design with F/4 on the DMD component.
This demonstrator permits the study of key parameters such as throughput, contrast and ability to remove unwanted
sources in the FOV (background, spoiler sources), PSF effect, spectrum stability on the detector. This study will be
conducted in the visible with possible extension in the IR. A breadboard on an optical bench has been developed for a
preliminary determination of these parameters.
The demonstrator on the sky is then of prime importance for characterizing the actual performance of this new family of
instruments, as well as investigating the operational procedures on astronomical objects. This demonstrator will be
studied in order to be placed on the Telescopio Nazionale Galileo during next year.
The solar seeing monitor MISOLFA: presentation and first results
Show abstract
PICARD is a space mission developed to observe the Sun at high angular resolution. One of the main space
objectives of PICARD is to measure the solar diameter with few milli arc-seconds accuracy. A replica of the space
instrument will be installed at Calern Observatory in order to test our ability to make such measurement from
ground with enough accuracy. High angular resolution observations with ground-based instrument are however
limited by atmospheric turbulence. The seeing monitor MISOLFA is developed to give all observation conditions
at the same moments when solar images will be recorded with the twin PICARD instruments. They will be
used to link ground and space measurements. An overview of the PICARD mission and the solar ground-based
experiments will be ¯rst given. Optical properties of MISOLFA will be after presented. The basic principles to
measure atmospheric parameters and the methods used to obtain them from solar images will be given. Finally,
some recent results obtained at Calern Observatory will be presented and discussed.
EPOL: the exoplanet polarimeter for EPICS at the E-ELT
Show abstract
EPOL is the imaging polarimeter part of EPICS (Exoplanet Imaging Camera and Spectrograph) for the 42-m E-ELT. It
is based on sensitive imaging polarimetry to differentiate between linearly polarized light from exoplanets and
unpolarized, scattered starlight and to characterize properties of exoplanet atmospheres and surfaces that cannot be
determined from intensity observations alone. EPOL consists of a coronagraph and a dual-beam polarimeter with a
liquid-crystal retarder to exchange the polarization of the two beams. The polarimetry thereby increases the contrast
between star and exoplanet by 3 to 5 orders of magnitude over what the extreme adaptive optics and the EPOL
coronagraph alone can achieve. EPOL operates between 600 and 900 nm, can select more specific wavelength bands
with filters and aims at having an integral field unit to obtain linearly polarized spectra of known exoplanets. We present
the conceptual design of EPOL along with an analysis of its performance.
HAWCPol: a first-generation far-infrared polarimeter for SOFIA
Show abstract
We describe our ongoing project to build a far-infrared polarimeter for the HAWC instrument on SOFIA. Far-IR
polarimetry reveals unique information about magnetic fields in dusty molecular clouds and is an important
tool for understanding star formation and cloud evolution. SOFIA provides flexible access to the infrared as
well as good sensitivity to and angular resolution of continuum emission from molecular clouds. We are making
progress toward outfitting HAWC, a first-generation SOFIA camera, with a four-band polarimeter covering 50 to
220 microns wavelength. We have chosen a conservative design which uses quartz half-wave plates continuously
rotating at ~0.5 Hz, ball bearing suspensions, fixed wire-grid polarizers, and cryogenic motors. Design challenges
are to fit the polarimeter into a volume that did not originally envision one, to minimize the heating of the
cryogenic optics, and to produce negligible interference in the detector system. Here we describe the performance
of the polarimeter measured at cryogenic temperature as well as the basic method we intend for data analysis.
We are on track for delivering this instrument early in the operating lifetime of SOFIA.
The polarization optics for the European Solar Telescope (EST)
Show abstract
EST (European Solar Telescope) is a 4-m class solar telescope, which is currently in the conceptual design phase. EST
will be located at the Canary Islands and aims at observations with the best possible spectral, spatial and temporal
resolution and best polarimetric performance, of the solar photosphere and chromosphere, using a suite of instruments
that can efficiently produce two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic
properties of the plasma over many scale heights, and ranging from λ=350 until 2300 nm.
In order to be able to fulfill the stringent requirements for polarimetric sensitivity and accuracy, from the very beginning
the polarimetry has been included in the design work. The overall philosophy has been to use a combination of
techniques, which includes a telescope with low (and stable) instrumental polarization, optimal full Stokes polarimeters,
differential measurement schemes, fast modulation and demodulation, and accurate calibration.
The current baseline optical layout consists of a 14-mirror layout, which is polarimetrically compensated and nonvarying
in time. In the polarization free F2 focus ample space is reserved for calibration and modulators and a
polarimetric switch. At instrument level the s-, and p-planes of individual components are aligned, resulting in a system
in which eigenvectors can travel undisturbed through the system.
Progress on MMT-POL: the 1-5µm adaptive optics optimized polarimeter for the MMT
Show abstract
MMT-POL is an adaptive optics optimized imaging polarimeter for use at the 6.5m MMT. By taking full advantage of
the adaptive optics secondary mirror of the MMT, this polarimeter will offer diffraction-limited polarimetry with very
low instrumental polarization. This instrument will permit observations as diverse as protoplanetary discs, comets, red
giant winds, galaxies and AGN. We report on progress toward regular operation of MMT-POL, including early
laboratory calibration and optimization. Characterization of the 1-5μm Virgo array and supporting electronics is
included, as are tests of the polarimetry optics at the heart of this instrument.
A method to subtract the skylight for the multi-fiber instrument E-ELT/OPTIMOS-EVE
Show abstract
We present a new method to subtract sky light from faint object observations with fiber-fed spectrographs. The
algorithm has been developed in the framework of the phase A of OPTIMOS-EVE, an optical-to-IR multi-object
spectrograph for the future european extremely large telescope (E-ELT). The new technique overcomes the
apparent limitation of fiber-fed instrument to recover with high accuracy the sky contribution. The algorithm
is based on the reconstruction of the spatial fluctuations of the sky background (both continuum and emission)
and allows us to subtract the sky background contribution in an FoV of 7 × 7 arcmin2 with an accuracy of 1%
in the mono-fibers mode, and 0.3-0.4% for integral-field-unit observations.
The GREGOR Fabry-Perot interferometer: a new instrument for high-resolution solar observations
Show abstract
The GREGOR Fabry-P´erot Interferometer (GFPI) is one of the first-light instruments of the 1.5-meter GREGOR solar
telescope currently being commissioned at Observatorio del Teide (OT), Tenerife, Spain. A spectral resolution of
R ≈ 250, 000 over the wavelength range from 530-860 nm can be achieved using a tunable dual etalon system. A high
spectral resolving power is needed to extract physical parameters (e.g., temperature, plasma velocity and the magnetic
field vector) from inversions of photospheric and chromospheric spectral lines. The GFPI is outfitted with a polarimeter,
which accurately measures the full Stokes vector. Precision polarimetry is facilitated by a calibration unit in the immediate
vicinity of GREGOR's secondary focus. The GFPI operates close to the diffraction limit of GREGOR, thus providing
access to fine structures as small as 60 km on the solar surface. The field-of-view (FOV) of 52" × 40" is sufficiently
large to cover significant portions of active regions. Large-format, high-cadence CCD detectors are an integral part of the
instrument to ensure that scans of spectral lines can be obtained in time spans corresponding to the evolution time scale of
solar phenomena such as granulation, evolving magnetic fields or dynamic chromospheric features. Besides describing the
technical features of the GFPI and providing a status report on commissioning the instrument, we will use two-dimensional
spectropolarimetric data obtained with the Vacuum Tower Telescope (VTT) at OT to illustrate GFPI's science capabilities.
Progress report on FORCAST grism spectroscopy as a future general observer instrument mode on SOFIA
Show abstract
We have implemented and tested a suite of grisms that will enable a moderate-resolution mid-infrared spectroscopic
mode in FORCAST, the facility mid-infrared camera on SOFIA. We have tested the hardware for the spectral modes
extensively in the laboratory with grisms installed in the FORCAST filter wheels. The grisms perform as designed,
consistently producing spectra at resolving powers in the 200-1200 range at wavelengths from 5 to 38 microns. In
anticipation of offering this capability as a SOFIA general observer mode, we are developing software for reduction and
analysis of FORCAST spectra, a spectrophotometric calibration plan, and detailed plans for in-flight tests prior to
commissioning the modes. We present a brief summary of the FORCAST grism spectroscopic system and a status report.
E-ELT Instrument study for first light: OPTIMOS-DIORAMAS: mechanical concept study for slit masks system
Show abstract
The Seeing-limited, large multiplex, optical/near-IR spectrograph, Optimos-Dioramas, currently under study by a
Consortium of Institutes from France, Italy, and Switzerland, is one of the possible candidates for first light on the EELT
Telescope. The spectograph is designed to maximize the field of view and cover in one-shot the spectral range
(0.37micron - 1.6micron). This paper describes the studies performed to establish a base-line conceptual design of the
Slit Masks System for the Optimos-Dioramas spectrograph. This unit has been designed in order to better satisfy the
limits of the allowed volume on the Nasmyth E-ELT platform, and it is also able to guarantee all the optical
specifications needed to cover the overall field of view (7x7arcmin). In order to take and position the masks in the focal
plane, the performed system is fully robotic and able to load/unload the masks in the proper quadrant. A central cross
structure, about 8.33arcsec wide, is needed. Each mask will necessarily be larger than 719x719mm, i.e. 780x780mm.
The system based on four 0.6mm thick (black painted steel) masks is fully feasible and complies with all specifications.
Vignetting due to the focal plane curvature is minimized and the slits (cut via a stencil-laser machine) can have all shapes
and sizes.
OPTIMOS-EVE optical design of a very efficient, high-multiplex, large spectral coverage, fiber-fed spectrograph at EELT
Show abstract
OPTIMOS-EVE is a fiber-fed, high-multiplex, high-efficiency, large spectral coverage spectrograph for EELT covering
visible and near-infrared simultaneously. More than 200 seeing-limited objects will be observed at the same time over
the full 7 arcmin field of view of the telescope, feeding the spectrograph, asking for very large multiplexing at the
spectrograph side. The spectrograph consists of two identical units. Each unit will have two optimized channels to
observe both visible and near-infrared wavelengths at the same time, covering from 0.37 to 1.7 micron. To maximize the
scientific return, a large simultaneous spectral coverage per exposure was required, up to 1/3 of the central wavelength.
Moreover, different spectral resolution modes, spanning from 5'000 to 30'000, were defined to match very different sky
targets. Many different optical solutions were generated during the initial study phase in order to select that one that will
maximize performances within given constraints (mass, space, cost). Here we present the results of this study, with
special attention to the baseline design. Efforts were done to keep size of the optical components well within present
state-of-the-art technologies. For example, large glass blank sizes were limited to ~35 cm maximum diameter. VPH
gratings were selected as dispersers, to improve efficiency, following their superblaze curve. This led to scanning
gratings and cameras. Optical design will be described, together with expected performances.
Status of the Echelon-cross-Echelle Spectrograph for SOFIA
Show abstract
The Echelon-cross-Echelle Spectrograph (EXES) is one of the first generation instruments for the Stratospheric
Observatory for Infrared Astronomy (SOFIA). It operates at high, medium, and low spectral resolution in the
wavelength region 4.5 to 28.3 microns using a 1024x1024 Si:As detector array. From SOFIA, the high spectral
resolution mode (R ≈ 100,000) will provide truly unique data given the improved atmospheric transmission. We
are currently involved with system testing in preparation for our first ground-based telescope run to occur in
Jan 2011 at the NASA IRTF 3m. We present the current status of EXES including lab results in our high and
medium resolution modes, our plans for ground-based observing, and our expectations for operations on SOFIA.
Mechanical design of SIFS SOAR integral field unit spectrograph
Show abstract
The SOAR Integral Field Unit Spectrograph (SIFS) is fed by an integral field unit composed of a bi-dimensional
arrangement of 1300 optical fibers. It has been developed in Brazil by a team of scientists and engineers led by the
National Laboratory of Astrophysics (MCT/LNA) and the Department of Astronomy of the Institute of Astronomy,
Geophysics and Atmospheric Sciences of the University of São Paulo (IAG/USP). It comprises three major subsystems;
a fore-optics installed on the Nasmyth port of the telescope or the SOAR Adaptive Optics Module, a 14-m optical fiber
IFU, and a bench-mounted spectrograph installed on the telescope fork. SIFS is successfully assembled and tested on the
SOAR Telescope in Chile and has now moved to the commissioning phase. This paper reports on technical
characteristics of the mechanical design and the assembly, integration and technical activities.
The optical design of wide integral field infrared spectrograph
Show abstract
We present the optical design of the Wide Integral Field Infrared Spectrograph (WIFIS) which provides an unprecedented
combination of the integral field size and the spectral resolving power in the near-infrared wavebands.
The integral field size and spectral resolving power of WIFIS are ~ 5× 12on a 10-m telescope (or equivalently
13× 30on a 4-m telescope) and ~ 5300, respectively. Therefore, the affordable etendue of WIFIS is larger
than any other near-infrared integral field spectrographs while its spectral resolving power is comparable to the
highest value provided by other spectrographs. WIFIS optical system comprises an Offner relay-based pre-slit
unit, an image slicer for integral-field unit, a collimator, diffraction gratings, and a spectrograph camera. For the
integral field unit, WIFIS uses the Florida Image Slicer for Infrared Cosmological and Astrophysics which is a set
of 3 monolithic mirror arrays housing 22 image slicers. The collimator system consists of one off-axis parabola
and two lenses, while WIFIS relies on 3 different gratings to cover the entire JHK bands. The spectrograph
camera uses 6 lenses of CaF2 and SFTM16, delivering the f/3 final beam onto a Hawaii II RG 2K × 2K detector
array. WIFIS will be an ideal instrument to study the dynamics and chemistry of extended objects.
Design and status of a near-infrared multi-object spectrograph for the TAO 6.5-m Telescope
Show abstract
We describe the design and current status of a near-infrared multi-object spectrograph for the University of
Tokyo Atacama Observatory (TAO) project, which is to construct a 6.5m infrared telescope on the summit of
Co. Chajnantor (altitude of 5,460m) in the northern Chile. The instrument, named SWIMS (Simultaneous-color
Wide-field Infrared Multi-object Spectrograph), covers a wavelength range from 0.9 to 2.5 μm with a field of
view of 9.6 in diameter using 4096 × 4096 pixels with a pixel scale of 0.13 pixel-1. It has two observation
modes: a wide-field imager and a multi-object spectrograph (MOS). The MOS mode adopts cooled multi-slit
masks with 30 slits at a maximum, and achieves a spectral resolution of λ/▵λ~ 1000. Up to 20 masks can
be installed in a mask storage dewar. In both modes, two wavelength ranges of 0.9-1.4 μm and 1.4-2.5 μm
are observed simultaneously with a dichroic mirror placed in the collimated beam. This will provide us data
covering the wide spectral range under same conditions such as weather, telescope pointing, and so on. Such
data are important not only for redshift surveys of distant galaxies but also for rapidly time-variable events such
as gamma-ray bursts. As SWIMS is expected to be completed before the construction of the 6.5m telescope, we
plan to carry out performance verification and early scientific observations on the Subaru Telescope at Hawaii.
Design inputs for a high-performance high-resolution near-infrared spectrograph
Show abstract
The combination of immersion grating and infrared array detector technologies allows the construction of highresolution
spectrographs in the near-infrared that have capabilities similar to those of optical spectrographs. It is
possible, for instance, to design multi-object spectrographs with very large wavelength coverage and high throughput.
We explored the science and functional drivers for these spectrograph designs. Several key inputs into the design are
reviewed including risk, mechanical-optical trades, and operations. We discuss a design for a fixed configuration
spectrograph with either 1.1 - 2.5 or 3 - 5 μm simultaneous wavelength coverage.
KMOS data flow: reconstructing data cubes in one step
Show abstract
KMOS is a multi-object near-infrared integral field spectrometer with 24 deployable pick-off arms. Data processing
is inevitably complex. We discuss specific issues and requirements that must be addressed in the data
reduction pipeline, the calibration, the raw and processed data formats, and the simulated data. We discuss the
pipeline architecture. We focus on its modular style and show how these modules can be used to build a classical
pipeline, as well as a more advanced pipeline that can account for both spectral and spatial flexure as well as
variations in the OH background. A novel aspect of the pipeline is that the raw data can be reconstructed into
a cube in a single step. We discuss the advantages of this and outline the way in which we have implemented it.
We finish by describing how the QFitsView tool can now be used to visualise KMOS data.
The habitable zone planet finder: a proposed high-resolution NIR spectrograph for the Hobby Eberly Telescope to discover low-mass exoplanets around M dwarfs
Show abstract
The Habitable Zone Planet Finder (HZPF) is a proposed instrument for the 10m class Hobby Eberly telescope that will
be capable of discovering low mass planets around M dwarfs. HZPF will be fiber-fed, provide a spectral resolution R~
50,000 and cover the wavelength range 0.9-1.65μm, the Y, J and H NIR bands where most of the flux is emitted by midlate
type M stars, and where most of the radial velocity information is concentrated. Enclosed in a chilled vacuum vessel
with active temperature control, fiber scrambling and mechanical agitation, HZPF is designed to achieve a radial
velocity precision < 3m/s, with a desire to obtain <1m/s for the brightest targets. This instrument will enable a study of
the properties of low mass planets around M dwarfs; discover planets in the habitable zones around these stars, as well
serve as an essential radial velocity confirmation tool for astrometric and transit detections around late M dwarfs. Radial
velocity observation in the near-infrared (NIR) will also enable a search for close in planets around young active stars,
complementing the search space enabled by upcoming high-contrast imaging instruments like GPI, SPHERE and
PALM3K. Tests with a prototype Pathfinder instrument have already demonstrated the ability to recover radial velocities
at 7-10 m/s precision from integrated sunlight and ~15-20 m/s precision on stellar observations at the HET. These tests
have also demonstrated the ability to work in the NIR Y and J bands with an un-cooled instrument. We will also discuss
lessons learned about calibration and performance from our tests and how they impact the overall design of the HZPF.
Characterizing the Robert Stobie Spectrograph's near-infrared detector
Show abstract
We report on the detector testing status for the Robert Stobie Spectrograph's near-infrared arm. The instrument utilizes a
Teledyne HAWAII-2RG HgCdTe detector array with a 1.7 μm cutoff wavelength. We have selected an operating
temperature of 120 K. The characterization effort will take place in our detector-testing laboratory at the University of
Wisconsin-Madison. The laboratory is equipped with a test dewar, vacuum system, temperature controller,
monochromator, and warm detector test enclosure. We will measure detector performance characteristics such as readout
noise, gain, dark current, linearity, quantum efficiency, and persistence, and develop calibration strategies. Persistence
could have a substantial impact on the spectrograph's science data, and therefore, the development of mitigation
techniques for this effect will be emphasized.
Fourier transform spectroscopy on very large telescopes
Show abstract
While a premier technique for laboratory spectroscopy, Fourier transform (FT) spectroscopy has fallen into disuse in
astronomical applications. The speed of a FT spectroscopy is significantly less than that of a dispersive spectrograph
with an array detector due to multiplex disadvantage. However, there are a number of advantages of the FT technique
that can be exploited to offer spectroscopic capabilities that would otherwise not be available. For very large telescopes
these include spectral resolutions significantly in excess of 100000 and 2-D spectral spatial imaging. By using postdispersers
with array detectors the speed difference between cryogenic grating and FT spectrographs can be reduced. We
explore the possibilities of using pre-existing FT equipment upgraded with modern detectors on next generation
telescopes. For specificity, we will adopt as our model FTS at the 4-m Mayall telescope and study how it could be
adapted to an ELT, and with what resulting performance.
Quick-look reduction software for FORCAST grism mode on SOFIA
Show abstract
We have designed and fabricated a suite of grisms for use in FORCAST, a mid-infrared camera scheduled as a
first-light instrument on SOFIA. The grism suite gives SOFIA a new capability: low resolution spectroscopy from
5 to 38 microns at resolving powers from R=200 to R=1200, without the addition of a new instrument. We have
developed an IDL based spectral data reduction and quick-look software package, in anticipation of FORCAST
grism spectroscopy becoming a facility observing mode on the SOFIA telescope. The package allows users to
quickly view their data by extracting single-order and cross-dispersed spectra immediately after acquiring them
in flight. We have optimized the quick-look software to reduce the number of steps required to turn a set of
observations into a fully reduced extracted spectrum. We present a description of the philosophy of the data
reduction software, supplemented with screen shots and examples in hopes of garnering feedback and critiques
from potential end users, software developers, and instrument builders.
The Pathfinder testbed: exploring techniques for achieving precision radial velocities in the near infrared
Show abstract
The Penn State Pathfinder is a prototype warm fiber-fed Echelle spectrograph with a Hawaii-1 NIR detector that has
already demonstrated 7-10 m/s radial velocity precision on integrated sunlight. The Pathfinder testbed was initially setup
for the Gemini PRVS design study to enable a systematic exploration of the challenges of achieving high radial velocity
precision in the near-infrared, as well as to test possible solutions to these calibration challenges. The current version of
the Pathfinder has an R3 echelle grating, and delivers a resolution of R~50,000 in the Y, J or H bands of the spectrum.
We will discuss the on sky-performance of the Pathfinder during an engineering test run at the Hobby Eberly Telescope
as well the results of velocity observations of M dwarfs. We will also discuss the unique calibration techniques we have
explored, like Uranium-Neon hollow cathode lamps, notch filter, and modal noise mitigation to enable high precision
radial velocity observation in the NIR. The Pathfinder is a prototype testbed precursor of a cooled high-resolution NIR
spectrograph capable of high radial velocity precision and of finding low mass planets around mid-late M dwarfs.
Pressure and temperature stabilization of an existing Echelle spectrograph
Show abstract
The Echelle spectrograph FOCES,1 that was operated at the 2.2m Calar Alto telescope between 1995 and 2009
will be used as a test bed for a number of different stability issues related to high precision radial velocity
spectroscopy.
We utilize FOCES to study spectrograph stability, illumination stability and fiber transport stability.
The layout of this laboratory experiment will be presented in this paper together with the required and
desired spectrograph stability with respect to both pressure and temperature. We will present technical concepts
how to reach our stabilization goal as well as first results from the spectrograph thermal stabilization efforts.
Development of VIRUS alignment and assembly fixtures
Show abstract
The Visible Integral-Field Replicable Unit Spectrograph (VIRUS) Instrument is a set of 150+ optical spectrographs to
support observations for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). We plan to use a
production line assembly process to construct the large number of VIRUS units. This allows each sub-assembly of a
VIRUS unit to be interchangeable amongst all other VIRUS units. A production line manufacturing procedure will
enable various sub-assemblies to be built and tested in parallel. Examples of alignment and assembly fixtures required
for the VIRUS manufacturing process include a camera mirror alignment system, a collimator structure assembly device,
a collimator mirror mounting tool, and a grating alignment system. In this paper we describe the design of these fixtures
and their importance in the VIRUS assembly process.
Mechanical design evolution of the VIRUS instrument for volume production and deployment
Show abstract
The Visible Integral-Field Replicable Unit Spectrograph (VIRUS) is an integral field spectrograph to support
observations for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The VIRUS instrument is fed by
more than 33,000 optical fibers and consists of 150 spectrographs in 75 individual, identical units. This paper discusses
the evolution in mechanical design of the VIRUS unit spectrographs to maximize the cost benefit from volume
production. Design features which enable volume manufacture and assembly are discussed. Strategies for reducing
part count while enabling precision alignment are detailed. Design considerations for deployment, operation, and
maintenance en mass at the Hobby-Eberly Telescope are also made. In addition, several enabling technologies are
described including the use of cast aluminum in vacuum housings, use of cast Invar, and processing cast parts for
precision tolerances.
Development of a cryogenic system for the VIRUS array of 150 spectrographs for the Hobby-Eberly Telescope
Show abstract
The upcoming Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) has provided motivation for upgrading
the Hobby-Eberly Telescope (HET) at the McDonald Observatory. This upgrade includes an increase in
the field-of-view to accommodate the new and revolutionary Visible Integral-field Replicable Unit Spectrograph
(VIRUS). VIRUS is the instrument designed to conduct the HETDEX survey and consists of 150 individual
integral-field spectrographs fed by 33,600 total optical fibers covering the 22 arc-minute field-of-view of the
upgraded HET. The spectrographs are mounted in four enclosures, each 6.0×3.0×1.4 meters in size. Each
spectrograph contains a CCD detector that must be cryogenically cooled, presenting an interesting cryogenic
and vacuum challenge within the distribution system. In this paper, we review the proposed vacuum jacketed,
thermal siphon, liquid nitrogen distribution system used to cool the array of detectors and discuss recent developments.
We focus on the design, prototyping, and testing of a novel "make-break" thermal connector, built
from a modified cryogenic bayonet, that is used to quickly detach a single spectrograph pair from the system.
The LUCIFER MOS: a full cryogenic mask handling unit for a near-infrared multi-object spectrograph
Show abstract
The LUCIFER-MOS unit is the full cryogenic mask-exchange unit for the near-infrared multi-object spectrograph
LUCIFER at the Large Binocular Telescope. We present the design and functionality of this unique device. In LUCIFER
the masks are stored, handled, and placed in the focal plane under cryogenic conditions at all times, resulting in very low
thermal background emission from the masks during observations. All mask manipulations are done by a novel
cryogenic mask handling robot that can individually address up to 33 fixed and user-provided masks and place them in
the focal plane with high accuracy. A complete mask exchange cycle is done in less than five minutes and can be run in
every instrument position and state reducing instrument setup time during science observations to a minimum. Exchange
of old and new MOS masks is likewise done under cryogenic conditions using a unique exchange drive mechanism and
two auxiliary cryostats that attach to the main instrument cryostat.
mCorrecting METIS spectra for telluric absorption to maximize spectral fidelity
Show abstract
METIS is a mid-infrared instrument proposed for the European Extremely Large Telescope. It is designed to provide imaging and spectroscopic capabilities in the 3 - 14 micron region up to a spectral resolution of 100000. One of the novel concepts of METIS is that of a high-resolution integral field spectrograph for a diffraction-limited mid-IR instrument. While this concept has many scientific and operational advantages over a long-slit spectrograph, one drawback is that the spectral resolution changes over the field of view. This has an impact on the procedures to correct for telluric absorption lines imprinted on the science spectra. They are a major obstacle in the quest to maximize spectral fidelity, the ability to distinguish a weak spectral feature from the continuum. The classical technique of division by a standard star spectrum, observed in a single IFS spaxel, cannot simply be applied to all spaxels, because the spectral resolution changes from spaxel to spaxel. Here we present and discuss possible techniques of telluric line correction of METIS IFS spectra, including the application of synthetic model spectra of telluric transmission, to maximize spectral fidelity.
An image slicer-based integral-field spectrograph for EPICS
Show abstract
We present the results of a design study for an integral field spectrograph as the "back-end" instrument for spectroscopy
of exoplanets carried out in the context of the EPICS Phase A study. EPICS is the planet finder imager and spectrograph
for the E-ELT. In our study we investigated the feasibility of an image slicer based integral field spectrograph and
developed an optical design for the image slicer and the necessary pre-optics, as well as the spectrograph optics. We
present a detailed analysis of the optical performance of the design.
Using the X-shooter physical model to understand instrument flexure
Show abstract
We have developed a physical model of the VLT 2nd generation instrument X-shooter. The parameters of this
model, that describe the positions, orientations and other physical properties of the optical components in the
spectrograph, are continually updated by an optimisation process that ensures the best possible fit to arc lamp
line positions in calibration exposures. Besides its use in driving the wavelength calibration in the data reduction
pipeline, the physical model provides us with an insight into physical changes in the optical components and the
possibility to correlate these with changing instrument orientation. By utilising a continually growing database
of automatic flexure compensation exposures that cover a wide range of instrument orientations, we are able to
investigate flexure in terms of physical model parameters.
The upgraded WIYN bench spectrograph
Show abstract
We present the as-built design overview and post-installation performance of the upgraded WIYN Bench Spectrograph.
This Bench is currently fed by either of the general-use multi-fiber instruments at the WIYN 3.5m telescope on Kitt
Peak, the Hydra multi-object positioner, and the SparsePak integral field unit (IFU). It is very versatile, and can be
configured to accommodate low-order, echelle, and volume phase holographic gratings. The overarching goal of the
upgrade was to increase the average spectrograph throughput by ~60% while minimizing resolution loss (< 20%). In
order to accomplish these goals, the project has had three major thrusts: (1) a new CCD was provided with a nearly
constant 30% increase is throughput over 320-1000 nm; (2) two Volume Phase Holographic (VPH) gratings were
delivered; and (3) installed a new all-refractive collimator that properly matches the output fiber irradiance (EE90) and
optimizes pupil placement. Initial analysis of commissioning data indicates that the total throughput of the system has
increased 50-70% using the 600 l/mm surface ruled grating, indicating that the upgrade has achieved its goal.
Furthermore, it has been demonstrated that overall image resolution meets the requirement of <20% loss.
Gemini multi-object spectrograph focal plane CCD upgrade
Show abstract
The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory to
develop and implement a new focal plane assembly with an array of three Hamamatsu CCDs for the Gemini Multi-
Object Spectrographs[1,2]. This paper describes the overall design of the new focal plane system with respect to the
existing interface and requirements and outlines the test methodology to validate the new system against its performance
requirements. The characterization and performance optimization processes of the Hamamatus CCDs are also described.
Mechanical design of the near-infrared arm of the Robert Stobie Spectrograph for SALT
Show abstract
The Robert Stobie Spectrograph Near Infrared (RSS/NIR) upgrade for the Southern African Large Telescope (SALT)
extends the capabilities of the visible arm of RSS into the NIR. The RSS/NIR instrument is at the prime focus of SALT.
It is a versatile spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The
multiple modes and prime focus location introduce interesting engineering considerations. The spectrograph has an
ambient temperature collimator, cooled (-40ºC) dispersers and camera and a cryogenic detector. Many of the
mechanisms are required to operate within the cooled and cryogenic environments. The RSS/ NIR upgrade includes the
following mechanisms; an active flexure compensating fold mirror, a filter exchange mechanism, a Volume Phase
Holographic VPH grating exchange and rotation mechanism, an etalon inserter, a beam splitter inserter, an articulating
camera, internal camera focus and a cutoff filter exchange wheel. This paper gives an overview of the mechanical design
and focuses on some of the unique testing and prototyping tasks.
Design drivers for a wide-field multi-object spectrograph for the William Herschel Telescope
Show abstract
Wide-field multi-object spectroscopy is a high priority for European astronomy over the next decade. Most 8-10m
telescopes have a small field of view, making 4-m class telescopes a particularly attractive option for wide-field
instruments. We present a science case and design drivers for a wide-field multi-object spectrograph (MOS) with
integral field units for the 4.2-m William Herschel Telescope (WHT) on La Palma. The instrument intends to take
advantage of a future prime-focus corrector and atmospheric-dispersion corrector (Agocs et al, this conf.) that will
deliver a field of view 2 deg in diameter, with good throughput from 370 to 1,000 nm. The science programs cluster into
three groups needing three different resolving powers R: (1) high-precision radial-velocities for Gaia-related Milky Way
dynamics, cosmological redshift surveys, and galaxy evolution studies (R = 5,000), (2) galaxy disk velocity dispersions
(R = 10,000) and (3) high-precision stellar element abundances for Milky Way archaeology (R = 20,000). The multiplex
requirements of the different science cases range from a few hundred to a few thousand, and a range of fibre-positioner
technologies are considered. Several options for the spectrograph are discussed, building in part on published design
studies for E-ELT spectrographs. Indeed, a WHT MOS will not only efficiently deliver data for exploitation of
important imaging surveys planned for the coming decade, but will also serve as a test-bed to optimize the design of
MOS instruments for the future E-ELT.
LRS2: a new low-resolution spectrograph for the Hobby-Eberly Telescope
Show abstract
In the era of the Hobby-Eberly Telescope (HET) Wide-Field Upgrade (WFU), the current Low-Resolution Spectrograph
(LRS) will be replaced with a more capable red-optimized fiber instrument, called LRS2. This new spectrograph will be
based on the Visible Integral-field Replicable Unit Spectrograph (VIRUS) that was designed to be easily adapted to a
wide range of spectral resolutions, and wavelength ranges. The current snapshot of LRS2, fed by a 7x12 sq. arcsec fiber
integral-field unit (IFU), covers 350-1100 nm, simultaneously at a fixed resolving power R~1800, with the wavelength
range split into two pairs of spectrographs, one for the blue to red wavelength range (350-630 nm) and the other for the
red and far-red range (630-1100 nm). These units are designated LRS2-B and LRS2-R, respectively. Only minimal
modification from the base VIRUS design in gratings (for both pairs) and in the detector (for the red pair only) is
required. In addition to this flexibility, the generic nature and massively replicable characteristic of the instrument can
allow us to adapt the instrument to a wide range of not only telescope diameters (1 m ~ 40 m), but also observing modes
(single to multiple objects). We discuss the current snapshot of the LRS2 design.
Diverse field spectroscopy: instrument concepts
Show abstract
We are currently developing a range of instrument concepts which combine the advantages of integral field and multiobject
systems. They are modular, arbitrarily scalable, and will be capable of addressing large fields with extremely high
efficiency. We have coined the phrase 'Diverse Field Spectroscopy' to describe this paradigm shift in instrument
versatility. For such instruments, downselection to extract sub-sets of data from the focal plane is key. Whereas other
existing and proposed instruments (multiplex, multiple-field) use individual deployable fibres, IFUs or field pickoff
mechanisms to select regions from the field, the focus in Durham has been on implementing the downselection by means
of optical switches. We believe that optical switching will be a foundation-technology for future ELTs. Several of our
most promising concepts will be presented in this paper.
High-contrast observations with slicer-based integral field spectrographs 1: simulations
Show abstract
As part of the Phase A study for the EPICS instrument, we investigate if there are any contrast limitations imposed by
the choice of the integral field spectrograph (IFS) technology, and if so, to determine the contrast limits applicable to
each technology. In this document we investigate (through simulations) the contrast limitations inherent in a slicer based
IFS.
Current results show the achievable contrast with the slicer to be promising when taking into consideration the fact that
the central region of the apodized PSF has not been masked. Limiting the maximum intensity by a factor of 100-1000
using an obscuring focal plane mask should also reduce the intensity of the secondary speckles by an equivalent factor.
Furthermore, the secondary speckles created in the slicer spectrograph only influence the few slices where the bright
central core is imaged. By orienting these slices to lie along the spider arms of the E-ELT secondary, the fraction of the
field of view affected can be minimized.
High-contrast observations with slicer-based integral field spectrographs 2: experimental tests
Show abstract
As part of the Phase A study for the EPICS instrument, we investigate if there are any contrast limitations imposed by
the choice of the integral field spectrograph (IFS) technology, and if so, to determine the contrast limits applicable to
each technology. In this document we investigate (through production of a prototype and actual laboratory tests) the
contrast limitations inherent in a slicer based IFS.
Using an experimental set-up that generates speckles at the input to a slicer based integral field spectrograph, we have
conclusively demonstrated that a slicer based IFS (that has not been specifically designed for high contrast observations)
does NOT limit the contrast achieved by a planet finding instrument at the level of at least one part in 250 per spectral
channel at R~800. This limit is imposed by the limited source intensity available for the measurements made with the
test bed's current setup and is to be improved upon in the near future. This level of speckle noise rejection already
satisfies the top level requirements of the EPICS instrument.
The design of dispersing elements for a highly segmented, very wide-field spectrograph
Show abstract
Wide field spectrograph at the largest optical telescopes will be decisive to address the main open questions in modern
astrophysics. The key feature of this instrument is the modular concept: the spectrograph is the combination of about one
thousand identical small cameras, each carrying a few slits and operating at low to moderate spectral resolution, to be
illuminated at the Cassegrain focus of an existing 8m class telescope. The dispersing element to be used in these small
cameras has to satisfy some requirements in term of efficiency, resolution, size, small series production. Moreover the
cameras have to work both in imaging and spectroscopy modes, therefore a GRISM configuration of the dispersing
element is suitable. Based on these considerations, we have focused our attention to Volume Phase Holographic Gratings
(VPHGs) since they show large peak efficiency in the target spectral range (400-800 nm), they can be arranged in a
GRISM configuration reaching relative large resolution. The main constrains concern the available room for the
dispersing element, indeed the camera design is very compact. As a consequence, slanted VPHGs are studied and
optimized in combination with normal and Fresnel prisms.
New generation multichannel subtractive double pass for EST imaging spectropolarimetry
Frédéric Sayède,
Pierre Mein,
Jean-Philippe Amans,
et al.
Show abstract
Any future solar telescope project should incorporate an imaging spectrometer. For the future EST (European Solar
Telescope) the Observatoire de Paris offers an imaging spectro-porarimetry instrument: a new generation of MSDP. To
validate this new generation, we develop a beam slicer prototype that will be tested and validated on optical bench and
on existing telescopes. The study assesses the performance gain of such an instrument on a solar 4m class telescope. We
present opto-mechanical solutions of a new beam splitter and its implementation in EST.
METIS: system engineering and optical design of the mid-infrared E-ELT instrument
Show abstract
METIS is a mid-infrared instrument proposed for the European Extremely Large Telescope (E-ELT). It is designed to
provide imaging and spectroscopic capabilities in the 3μm to 14μm region up to a spectral resolution of 100.000. Here
the technical concept of METIS is described which has been developed based on an elaborated science case which is
presented elsewhere in this conference.
There are five main opto-mechanical modules all integrated into a common cryostat: The fore-optics is re-imaging the
telescope focal plane into the cryostat, including a chopper, an optical de-rotator and an un-dispersed pupil stop. The
imager module provides diffraction limited direct imaging, low-resolution grism spectroscopy, polarimetry and
coronagraphy. The high resolution IFU spectrograph offers a spectral resolution of 100.000 for L- and M-band and
optional 50.000 for the N-band. In addition to the WFS integrated into the E-ELT, there is a METIS internal on-axis
WFS operating at visual wavelengths. Finally, a cold (and an external warm) calibration unit is providing all kinds of
spatial and spectral calibrations capabilities. METIS is planned to be used at one of the direct Nasmyth foci available at
the E-ELT.
This recently finished Phase-A study carried out within the framework of the ESO sponsored E-ELT instrumentation
studies has been performed by an international consortium with institutes from Germany, Netherlands, France, United
Kingdom and Belgium.
The Infrared Imaging Spectrograph (IRIS) for TMT: sensitivities and simulations
Show abstract
We present sensitivity estimates for point and resolved astronomical sources for the current design of the
InfraRed Imaging Spectrograph (IRIS) on the future Thirty Meter Telescope (TMT). IRIS, with TMT's
adaptive optics system, will achieve unprecedented point source sensitivities in the near-infrared (0.84 - 2.45
μm) when compared to systems on current 8-10m ground based telescopes. The IRIS imager, in 5 hours of
total integration, will be able to perform a few percent photometry on 26 - 29 magnitude (AB) point sources
in the near-infrared broadband filters (Z, Y, J, H, K). The integral field spectrograph, with a range of scales
and filters, will achieve good signal-to-noise on 22 - 26 magnitude (AB) point sources with a spectral
resolution of R=4,000 in 5 hours of total integration time. We also present simulated 3D IRIS data of resolved
high-redshift star forming galaxies (1 < z < 5), illustrating the extraordinary potential of this instrument to
probe the dynamics, assembly, and chemical abundances of galaxies in the early universe. With its finest
spatial scales, IRIS will be able to study luminous, massive, high-redshift star forming galaxies (star
formation rates ~ 10 - 100 MΘ yr-1) at ~100 pc resolution. Utilizing the coarsest spatial scales, IRIS will be
able to observe fainter, less massive high-redshift galaxies, with integrated star formation rates less than 1
MΘsensitivity compared to current integral field spectrographs. The
combination of both fine and coarse spatial scales with the diffraction-limit of the TMT will significantly
advance our understanding of early galaxy formation processes and their subsequent evolution into presentday
galaxies.
The Infrared Imaging Spectrograph (IRIS) for TMT: on-instrument wavefront sensors (OIWFS) and NFIRAOS interface
Show abstract
The InfraRed Imaging Spectrograph (IRIS) is a first light client science instrument for the TMT observatory that
operates as a client of the NFIRAOS facility multi-conjugate adaptive optics system. This paper reports on the
concept study and baseline concept design of the On-Instrument WaveFront Sensors (OIWFS) and NFIRAOS
interface subsystems of the IRIS science instrument, a collaborative effort by NRC-HIA, Caltech, and TMT AO
and Instrument teams. This includes work on system engineering, structural and thermal design, sky coverage
modeling, patrol geometry, probe optics and mechanics design, camera design, and controls design.
Upgrade of VISIR the mid-infrared instrument at the VLT
Show abstract
The European Southern Observatory (ESO) is preparing to upgrade VISIR, the mid-IR imager and spectrograph at the
VLT. The project team is comprised of ESO staff and members of the original consortium that built VISIR: CEA Saclay
and ASTRON. The goal is to enhance the scientific performance of VISIR and to facilitate its use by the ESO
community. In order to capture the needs of the user community, we collected input from the users by means of a webbased
questionnaire. In line with the results of the internal study and the input from the user community, the upgrade
plan calls for a combination measures: installation of improved hardware, optimization of instrument operations and
software support. The limitations of the current detector (sensitivity, cosmetics, artifacts) have been known for some
time and a new 1k x 1k Si:As Aquarius array (Raytheon) will be the cornerstone of the VISIR upgrade project. A
modified spectroscopic mode will allow covering the N-band in a single observation. Several new scientific modes (e.g.,
polarimetry, coronagraphy) will be implemented on a best effort basis. In addition, the VISIR operational scheme will be
enhanced to ensure that optimal use of the observing conditions will be made. Specifically, we plan to provide a means
to monitor precipitable water vapour (PWV) and enable the user to specify it as a constraint set for service mode
observations. In some regions of the mid-IR domain, the amount of PWV has a fundamental effect on the quality of a
given night for mid-IR astronomy. The plan also calls for full support by ESO pipelines that will deliver science-ready
data products. Hence the resulting files will provide physical units and error information and all instrumental signatures
will have been removed. An upgraded VISIR will be a powerful instrument providing diffraction-limited performance at
an 8-m telescope. Its improved performance and efficiency as well as new science capabilities will serve the needs of the
ESO community but will also offer synergy with various other facilities such as ALMA, JWST, VLTI and SOFIA. A
wealth of targets for detailed study will be available from survey work done by VISTA and WISE. Finally, the upgraded
VISIR will also serve as a pathfinder for potential mid-IR instrumentation at the European Extremely Large Telescope
(E-ELT) in terms of technology as well as operations.
DAVINCI: a high-performance imager and integral field spectrograph for the W. M. Keck Observatory's next-generation adaptive optics facility
Show abstract
In this paper we report on the preliminary design of DAVINCI, the first light science instrument for the W. M. Keck
Observatory's Next Generation Adaptive Optics facility. DAVINCI will provide imaging and coronagraphy at the
diffraction limit from 0.7 μm to 2.4 μm over a field of ~30", and integral field spectroscopy with three sampling scales
(10, 35, and 50 mas) and a field of view of 5.6" x 3" for the largest (50 mas) sampling scale. The science requirements
for DAVINCI are discussed, followed by an examination of the challenges of designing the instrument within a strict
limit on overall cost. The instrument's optical design and opto-mechanical configuration is described as well as the
current performance predictions for the instrument.
Data simulator for the HERMES instrument
Show abstract
The HERMES instrument is a high resolution multi-object fiber-fed spectrograph (R~30,000) in development for the
Anglo-Australian Telescope (AAT), covering the wavelength range (370-1000 nm). Given the sophistication of
HERMES we have developed an end-to-end data simulator that accurately models the predicted detector images. The
data simulator encompasses all aspects of the transmission and optical aberrations of the light path: from the science
object, through the atmosphere, telescope, fibers, spectrograph and finally the camera detectors. The simulator uses
optical information derived from ZEMAX software that has been processed and verified using MATLAB software. The
simulator is sufficiently flexible to model other fiber spectrographs. In addition to helping validate the instrument
design, the resulting simulated images will be used to develop the required data reduction software. In this paper, we
present the simulator overview, requirements, specifications, system model, verification and simulation results.
Performance predictions for the Robert Stobie spectrograph near infrared arm on SALT
Show abstract
The Robert Stobie Spectrograph near infrared arm will provide high throughput, low to medium resolution long slit and
multi-object spectroscopy with broadband, spectropolarimetric, and Fabry-Perot imaging modes over a 8' diameter field
of view. The wavelength range of the instrument is 0.9-1.7 microns, and can be operated simultaneously with the visible
arm to extend the short wavelength limit to 0.32 microns. Once fielded, RSS-NIR will be the only facility instrument on
an 8-10 meter class telescope with multi-object spectroscopy capability covering this spectral range simultaneously.
RSS-NIR is scheduled to be commissioned on the 11-meter Southern African Large Telescope in late 2012. This is an
upgrade to the existing visible instrument, with which it shares the slit plane and an ambient temperature collimator.
Beyond the collimator, the NIR arm is cooled to -40 °C, with a cryogenic dewar containing the detector, long
wavelength blocking filters, and final camera optics. This semi-warm configuration has required extensive upfront
analysis of the instrumental thermal background levels, which have been incorporated into the instrument performance
simulator. We present the performance predictions for spectroscopic modes of RSS-NIR and preliminary performance
estimates and NIR issues still being addressed in the design for Fabry-Perot and polarimetric modes.
LUCIFER1: performance results
Show abstract
LUCIFER1 is a NIR camera and spectrograph installed at the Large Binocular Telescope (LBT). Working in
the wavelength range of 0.9-2.5micron, the instrument is designed for direct imaging and spectroscopy with 3
different cameras. A set of longslit masks as well as up to 23 user defined (MOS) masks are available. The set
of user defined masks can be exchanged while the instrument is at operating temperature.
Extensive tests have been done on the electro-mechanical functions, image motion due to flexure, optical
quality, instrument software, calibration and especially on the multi-object spectroscopy. Also a detailed characterization
of the instrument's properties in the different observing modes has been carried out. Results are
presented and compared to the specifications.
Precise infrared radial velocimetry with the Triplespec Exoplanet Discovery Instrument: current performance and results
Show abstract
The TripleSpec Exoplanet Discovery Instrument (TEDI) is optimized to detect extrasolar planets orbiting midto-
late M dwarfs using the Doppler technique at infrared wavelengths. TEDI is the combination of a Michelson
interferometer and a moderate-resolution near-infrared spectrograph, TripleSpec, mounted on the Cassegrain
focus of the Palomar 200-inch Hale Telescope. Here we present results from observations of a radial velocity
standard star and a laboratory source over the past year. Our results indicate that focus effects within the
interferometer, combined with non-common-path errors between the ThAr calibration source and starlight, limit
our performance to several 100 m/s. An upgraded version of TEDI, TEDI 2.0, will eliminate this behavior by
mixing ThAr with starlight in a scrambled fiber before a redesigned interferometer with minimal focal effects.
The Oxford SWIFT Spectrograph: first commissioning and on-sky results
Show abstract
The Oxford SWIFT spectrograph, an I & z band (6500-10500 A) integral field spectrograph, is designed to operate as a
facility instrument at the 200 inch Hale Telescope on Palomar Mountain, in conjunction with the Palomar laser guide star
adaptive optics system PALAO (and its upgrade to PALM3000). SWIFT provides spectra at R(≡λ/▵λ)~4000 of a
contiguous two-dimensional field, 44 x 89 spatial pixels (spaxels) in size, at spatial scales of 0.235";, 0.16", and 0.08" per
spaxel. It employs two 250μm thick, fully depleted, extremely red sensitive 4k X 2k CCD detector arrays (manufactured
by LBNL) that provide excellent quantum efficiency out to 1000 nm.
We describe the commissioning observations and present the measured values of a number of instrument parameters. We
also present some first science results that give a taste of the range of science programs where SWIFT can have a
substantial impact.
Mechanical configurations for the reionization and transients infrared camera (RATIR)
Alejandro Farah,
Everardo Barojas,
Nathaniel R. Butler,
et al.
Show abstract
RATIR (The Reionization and Transients Infrared Camera/Telescope) is an optical infrared camera in the 1.5 m telescope
in the Mexican National Astronomical Observatory, OAN, in San Pedro Martir, Baja California. The primary goal of
RATIR is to remotely observe Gamma Ray Bursts as detected by the SWIFT satellite. This document describes the
problem definition, the mechanical calculations, the conceptual design, the finite element analysis, the different
configurations proposed and the mechanical performance of the main Support Structure and Dichroic Mounts for RATIR.
Upgraded GMOS-N science detectors: schedule and commissioning plans
Show abstract
We present plans for the commissioning of the new GMOS-N red-sensitive science detectors, currently being integrated
into a new focal plane assembly at the NRC HIA. These Hamamatsu CCDs provide significantly higher quantum
efficiency than the existing detectors at red optical wavelengths (longward of ~ 700 nm), with > 80% QE at 900 nm
falling to ~10% QE at 1.05 μm. This upgrade not only improves current operations with GMOS-N, but also opens new
spectral ranges and potential observing modes (eg. use with Altair, the Gemini-N AO module). Care has been taken to
ensure that Nod & Shuffle will still be supported, since accurate sky subtraction is increasingly important at longer
wavelengths due to the increased density of sky lines. The commissioning plan aims to demonstrate the improvement in
current modes while minimizing the period of GMOS-N downtime for science use. The science commissioning is
currently scheduled for mid-November 2010.
Experimental results of multi-stage four quadrant phase mask coronagraph
Show abstract
In the framework of exoplanet direct imaging, a few coronagraphs have been proposed to overcome the large flux ratio
that exists between the star and its planet. However, there are very few solutions that gather in the same time broad band
achromaticity, a small inner working angle (shortest angular distance for planet detection), a good throughput for the
planet light, and a mature technical feasibility. Here, we propose to use a combination of chromatic Four Quadrant Phase
Mask coronagraphs to achromatize the dephasing of this well-studied monochromatic coronagraph. After describing the
principle of the technique, we present preliminary results for a compact prototype. Contrast larger than 10000 are
reached with more than 250 nm of spectral bandwidth in the visible. Stability over time and effect of the filtering is also
discussed.
Ultraviolet compatibility tests of lens coupling fluids used in astronomical instrumentation
Show abstract
We report on extensive laboratory testing of the optical compatibility of immersion fluids often used in astronomical
instrumentation. A strong near-ultraviolet absorption feature is seen after incubating several fluids with polyurethane often
used in expansion bladders, and a lesser absorption in the farther UV with Viton O-Ring material. Substitute materials were
tested, many of which show no such absorption. This program was started in response to a strong UV feature which
developed over time in the Robert Stobie Spectrograph of the Southern African Large Telescope. A repair strategy was
successfully implemented.
Infrared radial velocimetry with TEDI: performance development
Show abstract
The TripleSpec - Exoplanet Discovery Instrument (TEDI) is a device to use interferometric spectroscopy for the radialvelocity
detection of extrasolar planets at infrared wavelengths (0.9 - 2.4 μm). The instrument is a hybrid of an
interferometer and a moderate resolution echelle spectrograph (TripleSpec, R=2,700,) at the Cassegrain focus of the
Palomar 200" telescope. We describe our experimental diagnostic program using laboratory sources and standard stars in
different optical configurations, along with performance analysis and results. We explain our instrumental upgrade
development to achieve a long-term performance that can utilize our demonstrated, < 10 m/s, short-term velocity
precision.
Second-earth imager for TMT (SEIT): a proposal and concept Description
Show abstract
Thirty Meter Telescope (TMT) will see its first light in 2018. We propose Second-Earth Imager for TMT (SEIT) as a
possible next generation instrument of TMT. The main purpose of the SEIT is direct detection of habitable planets
around M-type stars. The large aperture of the TMT allows us to directly image very faint planets close to the bright
central stars. In general the ground-based telescopes will suffer from speckles caused by static aberrations and high sky
background, which prevent us to directly detect reflective light from (super) Earths. Here, we propose a new concept for
both speckle and sky background suppressions by the use of an interferometric technique. The exozodiacal light is also
suppressed when it is a symmetric source. Thus, this concept suppresses symmetric sources and then enhances the
contrast of the SITE. In this paper, we will show the concept of the SEIT and our preliminary simulation results.
The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch Open Telescope
Show abstract
A wide-field birefringent filter for the barium II line at 455.4nm is developed in Irkutsk. The Barium line is excellent for
Doppler-shift measurements because of low thermal line-broadening and steep flanks of the line profile. The filter width
is 0.008nm and the filter is tunable over 0.4nm through the whole line and far enough in the neighboring regions. A fast
tuning system with servomotor is developed at the Dutch Open Telescope (DOT). Observations are done in speckle
mode with 10 images per second and Keller-VonDerLühe reconstruction using synchronous images of a nearby bluecontinuum
channel at 450.5nm. Simultaneous observation of several line positions, typically 3 or 5, are made with this
combination of fast tuning and speckle. All polarizers are birefringent prisms which largely reduced the light loss
compared to polarizing sheets. The advantage of this filter over Fabry-Perot filters is its wide field due to a large
permitted entrance angle and no need of polishing extremely precise surfaces. The BaII observations at the DOT occur
simultaneously with those of a fast-tunable birefringent H-alpha filter. This gives the unique possibility of simultaneous
speckle-reconstructed observations of velocities in photosphere (BaII) and chromosphere (H-alpha).
Gemini Planet Imager coronagraph testbed results
Show abstract
The Gemini Planet Imager (GPI) is an extreme AO coronagraphic integral field unit YJHK spectrograph destined
for first light on the 8m Gemini South telescope in 2011. GPI fields a 1500 channel AO system feeding an
apodized pupil Lyot coronagraph, and a nIR non-common-path slow wavefront sensor. It targets detection and
characterizion of relatively young (<2GYr), self luminous planets up to 10 million times as faint as their primary
star. We present the coronagraph subsystem's in-lab performance, and describe the studies required to specify
and fabricate the coronagraph. Coronagraphic pupil apodization is implemented with metallic half-tone screens
on glass, and the focal plane occulters are deep reactive ion etched holes in optically polished silicon mirrors. Our
JH testbed achieves H-band contrast below a million at separations above 5 resolution elements, without using
an AO system. We present an overview of the coronagraphic masks and our testbed coronagraphic data. We
also demonstrate the performance of an astrometric and photometric grid that enables coronagraphic astrometry
relative to the primary star in every exposure, a proven technique that has yielded on-sky precision of the order
of a milliarsecond.
APIC: Absolute Position Interfero Coronagraph for direct exoplanet detection: first laboratory results
Show abstract
For the detection and direct imaging of exoplanets, when the intensity ratio between a star and its orbiting
planet can largely exceed 106, coronagraphic methods are mandatory. In 1996, a concept of achromatic interferocoronagraph
(AIC) was presented by J. Gay and Y. Rabbia for the detection of very faint stellar companions,
such as exoplanets. In an earlier paper, we presented a modified version of the AIC permitting to determine the
relative position of these faint companions with respect to the parent star, a problem unsolved in the original
design of the AIC. Our modification lied in the use of cylindrical lens doublets as field rotator. By placing two
of them in one arm of the interferometric set-up of AIC, we destroyed the axis of symmetry induced by the
AIC's original design. Our theoretical study, along with the numerical computations, presented then, and the
preliminary test bench results aiming at validating the cylindrical lens doublet field rotation capability, presented
in this paper, show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around
the optic axis.
Results on fibre scrambling for high accuracy radial velocity measurements
Show abstract
We present in this paper experimental data on fibres and scramblers to increase the photometrical stability of the
spectrograph PSF. We have used round, square, octagonal fibres and beam homogenizers. This study is aimed to
enhance the accuracy measurements of the radial velocities for ESO ESPRESSO (VLT) and CODEX (E-ELT)
instruments.
Coronagraphic capability for HARMONI at the E-ELT
Show abstract
HARMONI is a proposed visible and near-infrared integral field spectrograph for the European Extremely Large
Telescope. We are exploring the merits of adding a coronagraphic capability to HARMONI, specifically targeted at
enabling observations of faint, nearby companions (primarily extra-solar planets) that require high contrast. Although
HARMONI is not fed by extreme adaptive optics, we show that substantial contrasts can be achieved by post-processing
of the hyperspectral data cube using spectral deconvolution. We make predictions of achievable contrast as a function of
coronagraph design, based on realistic models of the telescope's aberrations.
Oukaimeden Observatory: detection of exoplanet HD 189733b by the transit method
Show abstract
In this paper we report the detection and characterization of HD 189733b, the
peculiarity of this exoplanet is that the flow of the target star is decreased
significantly (~ 3%) during the transit. We determined the radius of the exoplanet
1.27 ± 0.03 RJ, the impact parameter 0.70 ± 0.02, and the inclination of the orbit
85.4 ± 0.1°. The transit of the extrasolar planet HD 189733b is already done using
the larger telescope. In this study, we used during the observation a telescope of
modest size.
The Visible Spectro-Polarimeter (ViSP) for the Advanced Technology Solar Telescope
Show abstract
The Visible Spectro-Polarimeter (ViSP) is one of the first light instruments for the Advanced Technology Solar
Telescope (ATST). It is an echelle spectrograph designed to measure three different regions of the solar spectrum in
three separate focal planes simultaneously between 380 and 1600nm. It will use the polarimetric capabilities of the
ATST to measure the full Stokes parameters across the line profiles. By measuring the polarization in magnetically
sensitive spectral lines the magnetic field vector as a function of height in the solar atmosphere, along with the
associated variation of the thermodynamic properties can be obtained. The ViSP will have a spatial resolution of 0.04
arc seconds over a 2 minute field of view (at 600nm). The minimum resolving power for all the focal planes is 180,000.
The spectrograph supports up to 5 diffraction gratings and is fully automated to allow for rapid reconfiguration.
Space-based photometric precision from ground-based telescopes
Show abstract
Ground-based telescopes supported by lidar and spectrophotometric auxiliary instrumentation can attain space-based
precision for all-sky photometry, with uncertainties dominated by fundamental photon counting statistics. Earth's
atmosphere is a wavelength-, directionally- and time-dependent turbid refractive element for every ground-based
telescope, and is the primary factor limiting photometric measurement precision. To correct accurately for the
transmission of the atmosphere requires direct measurements of the wavelength-dependent transmission in the direction
and at the time that the supported photometric telescope is acquiring its data. While considerable resources have been
devoted to correcting the effects of the atmosphere on angular resolution, the effects on precision photometry have
largely been ignored.
We describe the facility-class lidar that observes the stable stratosphere, and a spectrophotometer that observes NIST
absolutely calibrated standard stars, the combination of which enables fundamentally statistically limited photometric
precision. This inexpensive and replicable instrument suite provides the lidar-determined monochromatic absolute
transmission of Earth's atmosphere at visible and near-infrared wavelengths to 0.25% per airmass and the wavelengthdependent
transparency to less than 1% uncertainty per minute. The atmospheric data are merged to create a metadata
stream that allows throughput corrections from data acquired at the time of the scientific observations to be applied to
broadband and spectrophotometric scientific data. This new technique replaces the classical use of nightly mean
atmospheric extinction coefficients, which invoke a stationary and plane-parallel atmosphere. We demonstrate
application of this instrument suite to stellar photometry, and discuss the enhanced value of routinely provably precise
photometry obtained with existing and future ground-based telescopes.
Testing of a transmission-filter coronagraph for ground-based imaging of exoplanets
Show abstract
We present the latest laboratory test of a new coronagraph using one step-transmission filter at the visible wavelength.
The primary goal of this work is to test the feasibility and stability of the coronagraph, which is designed for the
ground-based telescope especially with a central obstruction and spider structures. The transmission filter is circular
symmetrically coated with inconel film on one surface and manufactured with a precisely position-controlled physical
mask during the coating procedure. At first, the transmission tolerance of the filter is controlled within 5% for each
circular step. The target contrast of the coronagraph is set to be 10-5~10-7 at an inner working angle around 5λ/D. Based
on the high-contrast imaging test-bed in the laboratory, the point spread function image of the coronagraph is obtained
and it has delivered a contrast better than 10-6 at 5λ/D. As a follow-up effort, the transmission error should be controlled
in 2% and the transmission for such filter will be optimized in the near infrared wavelength, which should deliver better
performances. Finally, it is shown that the transmission-filter coronagraph is a promising technique to be used for the
direct imaging of exoplanets from the ground.