This PDF file contains the front matter associated with SPIE Proceedings Volume 11447, including the Title Page, Copyright information, and Table of Contents.

We present the current status and future plan of the instruments at the Subaru Telescope. The Hyper Suprime- Cam, which is a wide-field optical imager at the prime-focus and started the science operation in 2014, has been extensively used for a large survey program and general open use observations. The Prime Focus Spectrograph started the commissioning of the first subsystem, the Metrology Camera System, in 2018 and has been continuing the installation of the other subsystems. As the third system of the wide-field instrumentation suite, ULTIMATE-Subaru has started preliminary design for the GLAO system and conceptual designs for the science instruments. We will also present the status, upgrades, and future plan of the other facility instruments and visiting instruments.

I provide an overview of Gemini's instrumentation efforts including our facility instrument, instrument upgrade, and visitor instrument programs. We currently have 4 facility instruments at various stages including GHOST, a high-resolution optical spectrograph commissioning at Gemini South; SCORPIO, an 8-channel, optical to infrared camera and spectrograph being built for Gemini South; an update of the popular IGRINS instrument for Gemini; and GNAO, the new adaptive optics facility at Gemini North. I describe our visitor instrument program highlighting the radial velocity spectrograph MAROON-X and the multi-IFU infrared MOAO spectrograph, GIRMOS. Our upgrade program includes a number of improvements to our GeMS MCAO system at Gemini South, GPI upgrades and relocation to Gemini North, adding a polarimetry capability at Gemini, and new IFUs for GNIRS. I will include some thoughts on future work at Gemini and the challenges of running such a large program.

The Paranal Instrumentation Programme is responsible for planning and delivering the instruments and the associated infrastructures needed to keep the VLT and La Silla Observatories at the forefront of ground-based astronomy. With the completion of commissioning of the AOF, ESPRESSO, the AO system for the four VLTI Auxiliary Telescopes (NAOMI) and the two VLTI instruments GRAVITY, MATISSE, Gravity for Matisse fringe tracking, all second generation VLT instruments are now offered to the users. CRIRES upgrade is currently in full commissioning at VLT and the exo-planet science instrument NIRPS spectrograph is on its way to the 3.6 m telescope at La Silla. By keeping the foreseen roadmap (start one new instrument or upgrade every year), the programme is now completing the AO imager and IFU ERIS, an upgrade of AOF narrow field mode: IRLOS and is integrating the two MOS Instruments MOONS and 4MOST. A dedicated La Silla NTT instrument to transient science SOXS is also in construction. Ph

Presented here is a review of the status of facility instruments at the Large Binocular Telescope Observatory (LBTO). These include: the prime-focus optical Large Binocular Cameras (LBCs); optical Multi-Object Double Spectrograph (MODS) for imaging and spectroscopy; and the two LBT Utility Camera in the Infrared (LUCIs) for imaging and spectroscopy, which include the commissioning of the Single conjugated adaptive Optics Upgrade for LBT (SOUL). Recently, the Potsdam Echelle Polarietric and Spectroscopic Instrument (PEPSI), a fiber-fed high resollution optical echelle spectrograph with polarimetry capabilities, has transitioned from a Principal Investigator (PI) instrument to a facility instrument. We discuss the ”binocular lifestyle” including the unique challenges of using LBT in three ways: Duplex mode, with identical configurations on both sides (effectively an 11.8 meter mirror); Fraternal Twin (same instruments with different configurations) or Mixed mode, (different instruments on each side) which gives observers two 8.4 meter telescopes to use; or 22.65 meters in interferometry (LBTI) mode. We also review recent changes in nighttime operations at the observatory in response to the COVID-19 pandemic and plans for the implementation of the Health and Instrument Performance plan for the Observatory (HIPO), a program to proactively monitor the health and stability of the facility instruments.

SOXS (Son Of X-Shooter) is a single object spectrograph, characterized by offering a wide simultaneous spectral coverage from U- to H-band, built by an international consortium for the 3.6-m ESO New Technology Telescope at the La Silla Observatory, in the Southern part of the Chilean Atacama Desert. The consortium is focussed on a clear scientific goal: the spectrograph will observe all kind of transient and variable sources discovered by different surveys with a highly flexible schedule, updated daily, based on the Target of Opportunity concept. It will provide a key spectroscopic partner to any kind of imaging survey, becoming one of the premier transient follow-up instruments in the Southern hemisphere. SOXS will study a mixture of transients encompassing all distance scales and branches of astronomy, including fast alerts (such as gamma-ray bursts and gravitational waves), mid-term alerts (such as supernovae and X-ray transients), and fixed-time events (such as the close-by passage of a minor planet or exoplanets). It will also have the scope to observe active galactic nuclei and blazars, tidal disruption events, fast radio bursts, and more. Besides of the consortium programs on guaranteed time, the instrument is offered to the ESO community for any kind of astrophysical target. The project has passed the Final Design Review and is currently in manufacturing and integration phase. This paper describes the development status of the project.

The Large Lenslet Array Magellan Spectrograph (LLAMAS) is an NSF-funded facility-class Integral Field Unit (IFU) spectrograph under construction for the 6.5-meter Magellan Telescopes. It covers a 37" x 37" solid angle with 2,400 optical fibers efficiently coupled by a double-sided microlens-array, producing R = 2, 000 spectra with 0.7511 spatial resolution. Its broad passband from λ = 350 970nm offers access to line and continuum measurements over a wide range in redshift. Light is multiplexed by the IFU into 8 compact, carbon-fiber bench mounted spectrographs utilizing VPH grisms. We employed several trades on cost-performance ratio while optimizing LLAMAS’ system design including: (a) Splitting the passband between 3 fast all-refractive camera systems with modest entrance pupils, (b) limiting the fibers per unit (i.e. slit length) and building more spectrographs to leverage on production volume, and (c) using a commercial CCD camera built around a common detector (e2v 42-40) and thermoelectric + liquid cooling. To boost blue throughput and achieve high-quality sky subtraction the spectrograph cluster is mounted next to the focal plane on a folded Cassegrain port with gravity-invariant support. This also allows the instrument to deploy quickly, and be fully accessible within 10 minutes on any night, serving as a facility unit for observing astrophysical transients. A sub-sized IFU (169 fibers), mounted in a full-sized front end package with a single spectrograph (2 cameras) was delivered to Magellan in March 2020. We present as-measured laboratory performance from this prototype, though on-sky commissioning was unfortunately cancelled because of the COVID-19 pandemic. This contribution therefore focuses on subsequent design evolution and status of the full facility instrument.

Design and commissioning of the Circumgalactic H-alpha Spectrograph

The Cherenkov Telescope Array1 (CTA) is the next-generation ground-based observatory for very-high-energy gamma rays. The CTA consists of three types of telescopes with different mirror areas to cover a wide energy range (20 GeV–300 TeV) with an order of magnitude higher sensitivity than the predecessors. Among those telescopes, the Large-Sized Telescope (LST) is designed to detect low-energy gamma rays between 20 GeV and a few TeV with a 23 m diameter mirror. To make the most of such a large light collection area (about 400 m2), the focal plane camera must detect as much reflected Cherenkov light as possible. We have developed each camera component to meet the CTA performance requirements for more than ten years and performed quality-control tests before installing the camera to the telescope.2, 3 The first LST (LST-1) was inaugurated in October 2018 in La Palma, Spain (Figure 1).4 After the inauguration, various calibration tests were performed to adjust hardware parameters and verify the camera performance. In parallel, we have been developing the analysis software to extract physical parameters from low-level data, taking into account some intrinsic characteristics of the switched capacitor arrays, Domino Ring Sampler version 4 (DRS4), used for sampling the waveform of a Cherenkov signal. In this contribution, we describe the hard- ware design of the LST camera in Section 2, a procedure for low-level calibration in Section 3, and the readout e of the LST camera after the hardware calibration with a dedicated analysis chain in Section 4.

The first cross-calibration of a gamma-ray telescope array with a UAV-based system

Real-time detections of transients and rapid multi-wavelength follow-up are at the core of modern multi-messenger astrophysics. MeerTRAP is one such instrument that has been deployed on the MeerKAT radio telescope in South Africa to search for fast radio transients in real-time. This, coupled with the ability to rapidly localize the transient in combination with optical co-pointing by the MeerLICHT telescope gives the instrument the edge in finding and identifying the nature of the transient on short timescales. The commensal nature of the project means that MeerTRAP will keep looking for transients even if the telescope is not being used specifically for that purpose. Here, we present a brief overview of the MeerTRAP project. We describe the overall design, specifications and the software stack required to implement such an undertaking. We conclude with some science highlights that have been enabled by this venture over the last 10 months of operation.

The Integration and Verification Testing and characterization of the expected performance of the Large Synoptic Survey Telescope (LSST) Camera is described. The LSST Camera will be the largest astronomical camera ever constructed, featuring a 3.2 Gpixel focal plane mosaic of 189 CCDs. In this paper, we describe the verification testing program developed in parallel with the integration of the Camera, and the results from our performance characterization of the Camera. Our testing program includes electro-optical characterization and CCD height measurements of the focal plane, at several steps during integration, as well as a complete functional and characterization program for the finished focal plane. It also includes a suite of functional tests of the major Camera mechanisms: shutter, filter exchange system and thermal control. Finally, we expect to test the fully assembled Camera prior to its scheduled completion and delivery to the LSST observatory in early calendar 2021.

Rubin Observatory’s Commissioning Camera (ComCam) is a 9 CCD direct imager providing a testbed for the final telescope system just prior to its integration with the 3.2-Gigapixel LSSTCam. ComCam shares many of the same subsystem components with LSSTCam in order to provide a smaller-scale, but high-fidelity demonstration of the full system operation. In addition, a pathfinder version of the LSSTCam refrigeration system is also incorporated into the design. Here we present an overview of the final as-built design, plus initial results from performance testing in the laboratory. We also provide an update to the planned activities in Chile both prior to and during the initial first-light observations.

Results of a conceptual design study of ULTAIMTE-Wide Field Imager (WFI) is presented. ULTIMATE-WFI is a near-infrared wide-field imager for the ground-layer adaptive optics system of the Subaru telescope (ULTIMATESubaru) which realizes a 0. 002 seeing size over 200diameter at the Cassegrain focus utilizing a deformable 2ndry mirror. WFI has a 15. 07×15. 07 FoV with a wavelength coverage of 0.9–2.5µm. The FoV is covered by four identical optics, each having a square field lens with 226mm on a side. Its effective FoV is 7. 02 on a side, and is covered by a HAWAII-4RG array detector with a pixel scale of 0. 0011/pix. Effective FoV will be 14. 04×14. 04 or 2070 in total. Spot sizes at a detector plane are less than 0. 001 over the wavelength coverage. Due to the large FoV, vignetting by the telescope structure occurs and an additional cold stop is necessary to block their thermal emission, which causes ~80% vignetting at the edge of the FoV. All the optics are contained in a cylindrical structure to be installed on the Cassegrain focus of the telescope, and kept under cryogenic temperature except for the field lenses. Gravitational deformation will be smaller than 1mm, and may have negligible impact on the final image quality.

Dome C, Antarctica is unique in particular for long-duration astronomical observations due to the excellent weather conditions and nearly uninterrupted nights during the Southern winter period. The 40 cm telescope ASTEP has been operating successfully at the Concordia base, at Dome C, since 2010. We describe the new ASTEP+, a major upgrade of its camera box which will allow it to observe simultaneously in two colors. Approximately three times more photons will be collected for science, yielding more sensitive and accurate observations. The southern location of the telescope means that it is ideally located to follow-up exoplanetary targets in preparation for the future JWST and Ariel observations, in particular when located in the southern continuous viewing zones of these space-based telescopes.

TANGO -Tibet and Antarctica Network Ground Observatories is a new way to advance astrophysical knowledge towards a better understanding of the Universe for less money. TANGO is a novel ground-based telescope concept with a performance that is robotic optical half to 1-m telescopes running under extreme weather and human conditions, with long uninterrupted continuous precision observations from the ground. TANGO is dedicated to Stellar physics and Cosmology studies. Specially, variable objects and gamma ray burst observations, space surveillance and tracking operations. Telescopes are located in the best seeing and inaccessible sites in the world. TANGO achieves constituted by several and identical robotic telescopes with a wide field of view and high photometric and spectroscopic accuracy, technically based on our instrumentation expertize, such as PAIX, the first Robotic Antarctica Polar Mission, located in the heart of Antarctic.

BlueMUSE is a blue-optimised, medium spectral resolution, panoramic integral field spectrograph based on the MUSE concept and proposed for the Very Large Telescope. With an optimised transmission down to 350 nm, a larger FoV (1.4 × 1.4 arcmin2) and a higher spectral resolution (λ/Δλ ~ 4000) compared to MUSE, BlueMUSE will open up a new range of galactic and extragalactic science cases allowed by its specific capabilities in the 350-580nm range, beyond those possible with MUSE. In this paper, we present the optomechanical architecture and design of BlueMUSE at pre-phase A level, with a particular attention to some original aspects such as the use of curved detectors.

Exoplanets are abundant in our galaxy and yet characterizing them remains a technical challenge. Solar System planets provide an opportunity to test the practical limitations of exoplanet observations with high signal-to-noise data that we cannot access for exoplanets. However, data on Solar System planets differ from exoplanets in that Solar System planets are spatially resolved while exoplanets are unresolved point-sources. We present a novel instrument designed to observe Solar System planets as though they are exoplanets, the Planet as Exoplanet Analog Spectrograph (PEAS). PEAS consists of a dedicated 0.5-m telescope and off-the-shelf optics, located at Lick Observatory. PEAS uses an integrating sphere to disk-integrate light from the Solar System planets, producing spatially mixed light more similar to the spectra we can obtain from exoplanets. This paper describes the general system design and early results of the PEAS instrument.

The Sunrise balloon-borne solar observatory carries a 1 m aperture optical telescope and provides us a unique platform to conduct continuous seeing-free observations at UV-visible-IR wavelengths from an altitude of higher than 35 km. For the next flight planned for 2022, the post-focus instrumentation is upgraded with new spectro- polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable of observing multiple spectral lines within the visible wavelength. A new spectro-polarimeter called the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is under development for observing near-IR wavelength ranges of around 770 nm and 850 nm. These wavelength ranges contain many spectral lines sensitive to solar magnetic fields and SCIP will be able to obtain magnetic and velocity structures in the solar atmosphere with a sufficient height resolution by combining spectro-polarimetric data of these lines. Polarimetric measurements are conducted using a rotating waveplate as a modulator and polarizing beam splitters in front of the cameras. The spatial and spectral resolutions are 0.2" and 2 105, respectively, and a polarimetric sensitivity of 0.03 % (1σ) is achieved within a 10 s integration time. To detect minute polarization signals with good precision, we carefully designed the opto-mechanical system, polarization optics and modulation, and onboard data processing.

We present the IBIS2.0 project, which aims to upgrade and to install the Interferometric BIdimensional Spectrometer at the solar Vacuum Tower Telescope (Tenerife, Spain) after its disassembling from the Dunn Solar Telescope (New Mexico, USA). The instrument is undergoing a hardware and software revision that will allow it to perform new spectropolarimetric measurements of the solar atmosphere at high spatial, spectral and temporal resolution in coordination with other ground- and space-based instruments. Here we present the new opto-mechanical layout and control system designed for the instrument, and describe future steps.

The Dark Energy Spectroscopic Instrument (DESI) is a Stage IV ground-based dark energy experiment that will measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 square degrees will be measured during the life of the experiment. We describe the installation of the major elements of the instrument at the Mayall 4m telescope, completed in late 2019. The previous prime focus corrector, spider vanes, and upper rings were removed from the Mayall’s Serrurier truss and replaced with the newlyconstructed DESI ring, vanes, cage, hexapod, and optical corrector. The new corrector was optically aligned with the primary mirror using a laser tracker system. The DESI focal plane system was integrated to the corrector, with each of its ten 500-fiber-positioner petal segments installed using custom installation hardware and the laser tracker. Ten DESI spectrographs with 30 cryostats were installed in a newly assembled clean room in the Large Coude Room. The ten cables carrying 5000 optical fibers from the positioners in the focal plane were routed down the telescope through cable wraps at the declination and hour angle axes, and their integral slitheads were integrated with the ten spectrographs. The fiber view camera assembly was installed to the Mayall’s primary mirror cell. Servers for the instrument control system replaced existing computer equipment. The fully integrated instrument has been commissioned and is ready to start its operations phase.

The recently commissioned Dark Energy Spectroscopic Instrument (DESI) will measure the expansion history of the universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope delivers light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe key aspects and lessons learned from the development, delivery and installation of the fiber system at the Mayall telescope.

PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is a very wide- field, massively multiplexed, and optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed in the 1.3 degree-diameter field of view. The spectrograph system has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously deliver spectra from 380nm to 1260nm in one exposure. The instrumentation has been conducted by the international collaboration managed by the project office hosted by Kavli IPMU. The team is actively integrating and testing the hardware and software of the subsystems some of which such as Metrology Camera System, the first Spectrograph Module, and the first on-telescope fiber cable have been delivered to the Subaru telescope observatory at the summit of Maunakea since 2018. The development is progressing in order to start on-sky engineering observation in 2021, and science operation in 2023. In parallel, the collaboration is trying to timely develop a plan of large-sky survey observation to be proposed and conducted in the framework of Subaru Strategic Program (SSP). This article gives an overview of the recent progress, current status and future perspectives of the instrumentation and scientific operation.

We present an update on the overall integration progress of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), now scheduled for first light in early-2021, with almost all components now arrived at the observatory. We also present a summary of the current planning behind the 5-year initial phase of survey operations, and some detailed end-to-end science simulations that have been implemented to evaluate the final on-sky performance after data processing. WEAVE will provide optical ground-based follow up of ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object (MOS) fibres, 20 mini integral field units, or a single large IFU for each observation. The fibres are fed to a single (dual-beam) spectrograph, with total of 16k spectral pixels, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with limited coverage in each arm at R~20000.

Based on the success of the SAMI integral field spectrograph (IFS) instrument on the Anglo-Australian Telescope (AAT), the capacity for large IFS nearby galaxy surveys on the AAT is being substantially expanded with a new instrument, Hector. The high fill-factor imaging fibre bundles ‘hexabundles’, of the type used on SAMI, are being improved and enlarged to cover 27-arcsec diameter. The aim is to reach 2 effective radii on most galaxies, where the galaxy rotation curve flattens and half of the angular momentum is accounted for. The boosted Hector spectral resolution of 1.3 Angstrom will enable higher order stellar kinematics to be measured on a larger fraction of galaxies than with any other IFS survey instrument. Hector will have 21 hexabundles over a 2-degree field feeding both the new Hector spectrograph and existing AAOmega spectrograph. Hector consists of new blue and red-arm spectrographs, coupled to the new high- efficiency hexabundles and a unique robotic positioner. The novel robotic positioning concept will compensate for varying telecentricity over the 2-degree-field of the AAT to recoup the light loss and correct the focus across the field. The main components are in hand, and prototypes are currently being tested ahead of commissioning in the next year. Hector will take integral field spectroscopy of 15,000 galaxies with z < 0.1 in the 4MOST WAVES-North and WAVES-South regions. The WAVES data, which will come later, will give the environment metrics necessary to relate how local and global environments influence galaxy growth through gas accretion, star formation and spins measured with Hector. The WALLABY ASKAP survey will trace HI gas across the Hector fields, which in combination with Hector will give a complete view of gas accretion and star formation.

The VIRUS2 instrument is a new fiber-fed multiplexed integral field spectrograph consisting of 6 units, each with 4 spectral channels, to provide large on-sky area coverage coupled with broad spectral coverage. VIRUS2 will be a new facility instrument on the McDonald Observatory 2.7 m Harlan J Smith Telescope. The instrument employs a novel beam-switch module within the fiber feed to split the light into the 4 spectral channels covering 370-930 nm at R~2000, while achieving a very compact and highly stable instrument. The design of VIRUS2 emphasizes stability and careful calibration, with scrambling in the beam-switch module, compact spectrograph format, and tight thermal control. This is the first time such measures have been employed at moderate spectral resolution. In this paper, we provide an overview of the instrument and the build status of the 24 spectrographs, dete ield units. VIRUS2 is funded by NSF and deployment is planned in the second half of 2021.

The Multi Object Optical and Near-infrared Spectrograph (MOONS) instrument is the next generation multi-object spectrograph for the VLT. This powerful instrument will combine for the first time: the large collecting power of the VLT with a high multipexing capability offered by 1000 optical fibres moved with individual robotic positioners and a novel, very fast spectrograph able to provide both low- and high-resolution spectroscopy simultaneously across the wavelength range 0.64μm - 1.8μm. Such a facility will provide the astronomical community with a powerful, world-leading instrument able to serve a wide range of Galactic, Extragalactic and Cosmological studies. Th final assembly, integration and verification phase of the instrument is now about to start performance testing.

The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of <6 million objects, designed to decode the history of the Milky Way, reveal the inner workings of stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe. The Local Volume Mapper (LVM) is a facility designed to provide a contiguous 2,500 deg2 integral-field survey over a 3.5 year period from Las Campanas Observatory in Chile. In this paper we provide an overview and status update for the LVM instrument (hereafter LVM-I). Each integral-field unit’s spaxel probes linear scales that are sub-parsec (Milky Way) to ∼10 pc (Magellanic Clouds) which is accomplished with an angular diameter of 36.900. LVM’s spectral resolution is R = λ/∆λ ∼ 4, 000 which probes velocities of 33 kms−1 (1 σ) from 365 nm to 950 nm. LVM uses four 16-cm telescopes feeding three spectrographs. One telescope carries the bulk of the science load with ∼1,800 fibers coupled to the field via a pair of lenslet arrays, two telescopes are used to measure the night sky spectra in fields that flank the science field, and a fourth telescope contemporaneously monitors bright standard stars to determine atmospheric extinction. We expect LVM-I to deliver percent-level precision on important line ratios down to a few Rayleigh. The three spectrographs are being built by Winlight corporation in France based on those for the Dark Energy Spectroscopic Instrument (DESI). In this paper we present the high-level system design of LVM-I including the lenslet-coupled fiber IFUs, telescopes, guiding+acquisition system, calibration systems, enclosures, and spectrographs.

A status overview of 4MOST is presented, a new high-multiplex, wide-field spectroscopic survey facility under construction for ESO's VISTA telescope at Paranal. Its key specifications are: a large field of view of 4.4 deg2 and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). The 4MOST system integration has commenced and the selection process for ESO community survey programmes has been started. This overview presents the expected performance of the instrument, the science the consortium expects to carry out, and the unique operational scheme of 4MOST.

The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is an adaptive optics-fed multi-object integral field spectrograph with a parallel imaging capability. GIRMOS implements multi-object adaptive optics (MOAO) for each of its spectrographs by taking advantage of the infrastructure offered by Gemini upcoming wide-field AO facility at Manua Kea. The instrument offers the ability to observe four objects simultaneously within the Gemini-North AO (GNAO) system’s field-of-regard or a single object by tiling the four fields that feed light to four separate spectrographs. Each integral field spectrograph has an independent set of selectable spatial scales (0.025", 0.05", and 0.1" /spaxel) and spectral resolution (R 3,000 and 8,000) within an operating band of 0.95 2.4µm. These spatial scales correspond to indvidual spectrograph fields of view of 1x1", 2X2" , and 4x4", respectively. GIRMOS’s imager offers Nyquist sampling of the diffraction limit in H-band over a 85x85" imaging field. The imager can function in a parallel data acquisition mode with just minor vignetting spectroscopic pick- offs when they are deployed.

We discuss the preliminary end-to-end optical design of an infrared multi-object integral-field spectrograph (GIRMOS) that is designed to take advantage of the multi-object adaptive optics corrected field at the Gemini telescope. GIRMOS’s optical design consists of object selection pick-offs, an adaptive optics (AO) system, and four identical Integral-Field Spectrographs (IFSes), which employ an image slicer to arrange the integral field along a slit. Each IFS can pick off the individual FOV of 1.0x1.0”, 2.0x2.0”, 4.0x4.0” over a 2’ diameter field-of-regard, at a spatial sampling of 25mas, 50mas, and 100mas, respectively. The pick-offs can also be configured in close-packed arrangement to image a single field. Spectral resolutions of R~3000 and 8000 are available in Y, J, H, and K-bands from 0.95 to 2.4μm.

The Fiber Optic Broad-band Optical Spectrometer (FOBOS) is a high-priority spectroscopic facility concept for the W. M. Keck Observatory. Here, we provide an update on the FOBOS conceptual design. FOBOS will deploy 1800 fibers across the 20-arcminute field-of-view of the Keck II Telescope. Starbugs fiber positioners will be used to deploy individual fibers as well as fiber-bundle arrays (integral field units, IFUs). Different combinations of active single fibers or IFUs can be selected to carry light to one of three mounted spectrographs, each with a 600-fiber pseudoslit. Each spectrograph has four wavelength channels, enabling end-to-end instrument sensitivity greater than 30% from 0.31-1.0 µm at a spectral resolution of R ~ 3500. With its high fiber density on a large telescope and modest field-of-view, FOBOS is optimized to obtain deep spectroscopy for large samples. In single- fiber mode, it will deliver premier spectroscopic reference sets for maximizing the information (e.g., photometric redshifts) that can be extracted from panoramic imaging surveys obtained from the forthcoming Rubin and Roman Observatories. Its IFUs will map emission from the circumgalactic interface between forming galaxies and the intergalactic medium at z ~ 2–3, and lay the path for multiplexed resolved spectroscopy of high-z galaxies aided by ground-layer and multi-object adaptive optics. In the nearby universe, its high sampling density and combination of single-fiber and IFU modes will revolutionize our understanding of the M31 disk and bulge via stellar populations and kinematics. Finally, with a robust and intelligent target and program allocation system, FOBOS will be a premier facility for follow-up of rare, faint, and transient sources that can be interleaved into its suite of observing programs. With a commitment to delivering science-ready data products, FOBOS will enable unique and powerful combinations of focused, PI-led programs and community-driven observing campaigns that promise major advances in cosmology, galaxy formation, time-domain astronomy, and stellar evolution.

The Magellan Infrared Multi-object Spectrograph (MIRMOS) is a near-infrared (NIR) multi-object spectrograph (MOS) and integral field unit (IFU) to be deployed at the Magellan 6.5-meter telescopes at Las Campanas Observatory. MIRMOS is designed to address frontier scientific questions in extragalactic, cosmological, and exoplanetary science. These scientific questions led us to spectrograph with an instantaneous wavelength range from 0.89-2.4 µm with a spectral resolution < 3, 700. The spectrograph is fed by a front end that switches between a robotic mechanical slit mask capable of deploying nearly 90 slits over a 13' x 3' field, or by an image slicer IFU with a wide field of 26" × 20". MIRMOS is currently under design at the Carnegie Observatories.

MAROON-X is a fiber-fed, red-optical, high precision radial velocity spectrograph recently commissioned at the Gemini North telescope on Mauna Kea, Hawai’i. With a resolving power of 85,000 and a wavelength coverage of 500–920 nm, it delivers radial velocity measurements for late K and M dwarfs with sub-50 cm s⁻¹ precision. MAROON-X is currently the only optical EPRV spectrograph on a 8 m-class telescope in the northern hemisphere and the only EPRV instrument on a large telescope with full access by the entire US comm report here on the results of the commissioning campaign in December 2019 and early science results.

NIRPS is a near-infrared (YJH bands), fiber-fed, high-resolution precision radial velocity (pRV) spectrograph currently under construction for deployment at the ESO 3.6-m telescope in La Silla, Chile. Through the use of a dichroic, NIRPS will be operated simultaneously with the optical HARPS pRV spectrograph and will be used to conduct ambitious planet-search and characterization surveys through a 720-night of guaranteed time allocation. NIRPS aims at detecting and characterizing Earth-like planets in the habitable zone of low-mass dwarfs and obtain high-accuracy transit spectroscopy of exoplanets. Here we present a summary of the full performances obtained in laboratory tests conducted at Université Laval (Canada), and the first results of the on-going on-sky commissioning of the front-end. Science operations of NIRPS is expected to start in late-2020, enabling significant synergies with major space and ground instruments such as the JWST, TESS, ALMA, PLATO and the ELT.

We report on our efforts to develop a whispering gallery mode resonator etalon as a tool for precision radial velocity observations to detect exoplanets. The crystalline MgF₂ etalon will be referenced to a compact fiber laser frequency comb, and will serve as the wavelength calibration source for a stabilized, high resolution, visible band spectrograph. The extreme stability required for the detection and characterization of exo-Earths orbiting solar-type stars will be achieved by employing a composite resonator structure with a compensating material to balance the resonator’s coefficients of thermal expansion and thermal refractivity. Progress in modeling the etalon to achieve single mode-like performance, and experiments to demonstrate broad-band (octave-spanning) ling to a white light source, are described.

The upcoming Extremely Large Telescopes (ELTs) are expected to have the collecting area required to detect potential biosignature gases in the atmosphere of rocky planets around nearby low-mass stars. Some efforts are currently focusing on searching for molecular oxygen (O₂), since O₂ is a known biosignature on Earth. One of the most promising methods to search for O₂ is transmission spectroscopy in which high-resolution spectroscopy is combined with cross-correlation techniques. In this method, high spectral resolution is required both to resolve the exoplanet’s O₂ lines and to separate them from foreground telluric absorption. While current astronomical spectrographs typically achieve a spectral resolution of 100,000, recent studies show that resolutions of 300,000 – 400,000 are optimal to detect O₂ in the atmosphere of earth analogs with the ELTs. Fabry Perot Interferometer (FPI) arrays have been proposed as a relatively low-cost way to reach these resolutions. In this paper, we present performance results for our 2-FPI array lab prototype, which reaches a resolving power of 600,000. We further discuss the use of multi-cavity etalons (dualons) to be resolution boosters for existing spectrographs.

The Keck Planet Imager and Characterizer (KPIC) is a purpose-built instrument to demonstrate new tech- nological and instrumental concepts initially developed for the exoplanet direct imaging field. Located downstream of the current Keck II adaptive optic system, KPIC contains a fiber injection unit (FIU) capable of combining the high-contrast imaging capability of the adaptive optic system with the high dispersion spectroscopy capability of the current Keck high resolution infrared spectrograph (NIRSPEC). Deployed at Keck in September 2018, this instrument has already been used to acquire high resolution spectra (R < 35, 000) of multiple targets of interest. In the near term, it will be used to spectrally characterize known directly imaged exoplanets and low-mass brown dwarf companions visible in the northern hemisphere with a spectral resolution high enough to enable spin and planetary radial velocity measurements as well as Doppler imaging of atmospheric weather phenomena. Here we present the design of the FIU, the unique calibration procedures needed to operate a single-mode fiber instrument and the system performance.

We will present the status of the next generation near-infrared (0.84 - 2.45 micron) imager and integral field spectrograph (IFS) instrument, Liger, that is being designed for the W. M. Keck Observatory. The Liger imager and IFS operates concurrently on-sky and are optimized to sample the Keck All-sky Precision Adaptive optics (KAPA) system. The Liger IFS design is able to offer new science capabilities by extending to bluer wavelength coverage, larger field of views, and range of spectral resolving powers. We will discuss the overall Liger technical design, science requirements, and implementation plans for the entire program.

A consortium of several Australian and European institutes – together with the European Southern Observatory (ESO) – has initiated the design of MAVIS, a Multi-Conjugate Adaptive Optics (MCAO) system for the ground- based 8-m Very Large Telescope (VLT). MAVIS (MCAO-assisted Visible Imager and Spectrograph) will deliver visible images and integral field spectrograph data with 2-3x better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, which are all targeting science at near-infrared wavelengths. MAVIS successfully passed its Phase A in May 2020. We present the motivations, requirements, principal design choices, conceptual design, expected performance and an overview of the exciting science enabled by MAVIS.

The Gemini Planet Imager (GPI) is a dedicated high-contrast imaging facility designed for the direct detection and characterization of young Jupiter mass exoplanets. After six yrs of operation at Gemini South, GPI has helped establish that Jovian planets are rare at wide separations, but have higher occurrence rates at small separations. This motivates an upgrade of GPI to achieve deeper contrasts, especially at small inner working angles, while leveraging its current capabilities. GPI has been funded to undergo a major science-driven upgrade as part of a relocation to Gemini North (GN). Gemini plans to remove GPI at the end of 2020A. We present the status of the proposed upgrades to GPI including a EMCCD-based pyramid wavefront sensor, broadband low spectral resolution prisms and new apodized-pupil Lyot coronagraph designs. We discuss the expected performance improvements in the context of GPI 2.0's enhanced science capabilities which are scheduled to be made available at GN in 2022.

In this paper we will give an overview of the status of the three instruments and one adaptive optics module that are currently under construction for the European Southern Observatory (ESO) Extremely Large Telescope (ELT). Currently three of those instruments are in the final design stages and the adaptive optics module, MAORY, is rapidly approaching its Preliminary Design Review (PDR). Funding for the laser tomographic module for HARMONI has been secured and that module is now included as part of that overall instrument project. The PDR phase of the instruments has strongly highlighted the ambitious nature of these and all 30-m class instrument projects. Scientifically, managerially and technically, the step up from the 8-m class is challenging. This paper will provide an introduction to all these instruments and will highlight some of the important developments required to realise them.

This paper presents an overview of the suite of science instruments envisioned for the Thirty Meter Telescope. Specifically, the we'll explore the evolution within our first light and first decade instruments.

HARMONI is the adaptive optics assisted, near-infrared and visible light integral field spectrograph for the Extremely Large Telescope (ELT). A first light instrument, it provides the work-horse spectroscopic capability for the ELT. As the project approaches its Final Design Review milestone, the design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument’s capabilities from a user perspective, provide a summary of the instrument’s design, including plans for operations and calibrations, and provide a brief glimpse of the predicted performance for a specific observing scenario. The paper also provides some details of the consortium composition and its evolution since the project commenced in 2015.

IRIS is a diffraction limited instrument designed for first light of the Thirty Meter Telescope (TMT). It combines a nearinfrared integral field spectrograph (lenslet array and mirror slicer) and a wide-field imager with platescales as small as 4 mas. The project is nearing the end of its final design phase and will soon be ready for fabrication. Our team has created a wide variety of prototypes and design solutions for this advanced instrument. While many challenges like atmospheric dispersion correction and saturation are particularly acute due to the telescope diameter, many others arise from the large format detector arrays and wide range of science goals. We’ll present the overall design, results from our prototyping activities and discuss the astrophysical opportunities.

MCAO is essential to perform astrometry with the Extremely Large Telescope (ELT). Differently from the 8m class telescopes, the ELT will be a fully adaptive telescope, and a significant portion of the Adaptive Optics (AO) dynamic range will be absorbed by the correction and stabilization of the telescope aberrations and instabilities. Of particular interest for the ground-based astrometry is the use of Multi-Conjugated AO systems that allow to stabilize the low order field distortions against the transient plate scale instabilities of different origin occurring at the telescope and in the instrument. The instruments have several optical elements relatively far away from the pupil that can potentially challenge the astrometric precision of the observations with their residual mid-spatial frequencies errors. Using a combined simulation of ray tracing and AO numerical codes we assess the impact of these systematic errors at different field of view scales and fitting scenarios. The distortions have been assessed at different sky Position Angles (PA) and indicate that over large field of views only small PA ranges (±1°-3°) are accessible with astrometric residuals 50 µas. A full compliance, at any PA is achievable for 2 arcsec² FoV patches already with a 3rd order polynomial. The natural partition of the optical system in three segments, ELT-MAORY-MICADO, respectively telescope, MCAO module and instrument, resembles also a splitting of the astrometric problem in the three subsystems that are characterized by different distortion amplitudes and calibration strategies. The result is a family portrait of the different optical segments with their prescription, dynamic motions, conjugation height and AO correctability, leading to trace their role in the bigger puzzle of the 50 μas astrometric endeavor.

In this paper we present the status of the Armazones Instrumentation Programme for ESO’s Extremely Large Telescope (ELT). While the ELT Construction Programme includes the first-generation instruments (MICADO, MAORY, HARMONI and METIS), the Armazones Programme covers the development of all future instrumentation for the ELT. As part of this Programme we have already completed 2 Phase-A studies for a high-resolution spectrograph (HIRES) and a multi-object spectrograph (MOSAIC). In this paper we report the status of the Programme, the complementarity of these new instruments with the ones already in construction, and the roadmap for future developments.

HIRES is the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing- and diffraction-limited modes. Its modularity will ensure that HIRES can be placed entirely on the Nasmyth platform, if enough mass and volume is available, or part on the Nasmyth and part in the Coud`e room. ELT-HIRES has a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (PopIII), tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers.

MANIFEST is a multi-object fibre positioner for the Giant Magellan Telescope that uses ‘Starbug’ robots to accurately position fibre units across the telescope’s focal plane. MANIFEST, when coupled to the telescope’s planned seeing-limited instruments, GMACS and GCLEF, offers access to: larger fields of view; higher multiplex gains; versatile focal plane reformatting of the focal plane via multiple integral-field-units; increased spectral resolution using image-slicers; the capability for simultaneous observations with multiple instruments; the possibility of a gravity-invariant spectrograph mounting; the potential for OH suppression via fiber systems in the near-infrared; and the versatility of adding new instruments in the future. We have now completed the pre-concept phase for MANIFEST. This phase has focused on developing the science case and requirements, further developing high risk aspects of the instrument design, designing the opto-mechanical interfaces to the GMACS and GCLEF instruments, and detailing the interfaces to the GMT.

MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51”) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. Here, we present the opto-mechanical design of the Relay Optics (RO), the optical system relaying the ELT focal plane to an accessible position for MICADO using the SCAO-only stand-alone observing mode. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat mirrors with motorized piston-tip-tilt mounts and three additional powered mirrors of up to ~500 mm in diameter, the MICADO calibration assembly, and a cover to protect all opto-mechanical components on top of the bench. A 9-point whiffletree support, combined with a thermal compensation system is implemented for the critical mirrors. The static and the dynamic performance of the MICADO RO are investigated through a detailed Finite Element Model (FEM), the results are combined with a Zernike basis representation of the mirror surface deformations performed in Zemax for assessing the optical performance.

HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from R (≡λ/Δλ) 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. The instrument uses a field splitter and image slicer to divide the field into 4 sub-units, each providing an input slit to one of four nearly identical spectrographs. This proceeding presents the final opto- mechanical design and the AIV plan of the spectrograph units.

The Giant Magellan Telescope (GMT) Commissioning Camera (ComCam) is an all-refractive, focal reducing camera intended for the evaluation of telescope performance in both natural seeing and ground layer adaptive optics modes across a six arcminute field of view. As the first purpose-built, large imager for the GMT, it also provides unique public outreach functions and scientific research opportunities by enabling both narrowband and broadband imaging and photometric measurements at wavelengths between 360 and 950 nm. In addition to a discrete set of narrowband and broadband filters, inclusion of a deployable Fabry-Perot etalon will greatly enhance ComCam’s capabilities. With an image scale of 0.06 arcseconds per pixel, ComCam will be able to take full advantage of the GMT’s GLAO-corrected image quality under the best predicted conditions. ComCam has undergone a conceptual design review and is now under development in the preliminary design phase. Instrumental first light will be concurrent with that of the GMT.

HARMONI is the first-light visible and near-IR integral field spectrograph for the E-ELT. Non-Common Path Aberrations between the Adaptive Optics channel and the science path are the main limitation for direct imaging of exoplanets. The next generation of Extremely Large Telescopes will require advanced techniques for NCPA calibration to exploit their full capabilities and open up a new era of exoplanet discoveries. Calibrating these aberrations with conventional techniques like Phase Diversity can become problematic when the instrument contains an image slicer (such as HARMONI and PCS for the E-ELT). In this context, we have characterised the impact of image slicers on the PSF, and developed an alternative approach to NCPA calibration based on Machine Learning, which can discriminate between intrinsic slicer effects and aberrations features in the PSF.

HARMONI is the first light visible and near-infrared (450 – 2450 nm, λ/Δλ = 3,000 – 17,000) integral field spectrograph for the European Southern Observatory’s Extremely Large Telescope. The path for scientific light includes pre-optics to set the field of view (4 – 60 mas), an integral field unit to reformat the rectangular field into four 540 mm long slits, and four spectrographs which collimate, disperse, and image the light. The spectrographs collimate the input slits using a system of three off-axis, aspheric mirrors which lack a common optical axis. We have demonstrated the alignment procedure of this three-mirror anastigmat in numerical simulations. We will initially align the collimator mirrors by measuring reference features with a coordinate measuring machine (CMM). We will then use an interferometer to measure the wavefront error (WFE) at positions along the input slit. These WFE measurements will be entered into a numerical model to optimize available compensators, and the corresponding adjustments will be applied to the collimator. This process of measuring WFE, using a model to determine optimal compensator adjustments, and applying the adjustments will be repeated until the performance has converged. As an initial demonstration of this method, we have simulated the full alignment procedure. The modelled systems include manufacturing errors, account for the uncertainty of values reported by mirror manufacturers, and simulate the CMM and interferometer alignment steps. Nearly all of 1000 instances meet our requirements after two iterations of the optical alignment, and all were found to satisfy our requirements after five iterations.

We present the current design status of the cryostat of the Mid-infrared ELT Imager and Spectrograph (METIS) instrument to be operated at ESO’s Extremely Large Telescope (ELT). The cryostat provides the cold optics of the instrument with the required cryo-vacuum environment. The radiation shields of the cryostat are cooled with liquid nitrogen and the cold optics is cooled via pulse-tube coolers down to temperatures around 35 K. The cold-warm interface is provided with G10 blades that build together with the top part of the cryostat vessel the structural interface to the cold optics, the warm support structure and the warm calibration source. The cryostat development is currently in its final design phase which is planned to conclude in summer 2022. We present in this paper the current design status, the key design considerations and the cooling concept.

MANIFEST, the Many Instrument Fiber System, is a fiber-positioner facility proposed for Giant Magellen Telescope (GMT) by Australian Astronomical Optics, Macquarie University (AAO MQ). It will use hundreds fiber robotic positioners ”Starbugs” to access telescope large focal plane and provides a means for the first light instruments GMACS and G-CLEF to increase their native capabilities. Since the concept was proposed, a lot of development has been made. In this paper, we will report the latest optical interface development between MANIFEST to GMACS and G-CLEF instrument during the pre-conceptual design study.

METIS, the mid-infrared imager and spectrograph for the wavelength range 2.9-14 µm (astronomical L-, M- and N bands), will be equipped with a calibration unit, developed at the University of Cologne, which task is to deliver simulated sources for the test and calibration of the main imaging and spectral functionalities of METIS. Our subsystem, as the full METIS instrument, is currently in the Phase C of the project, which leads to the Final Design Review expected by the end of 2021. In this contribution, we first briefly introduce the general concepts chosen for the Warm Calibration Unit (WCU) and then detail the laboratory work that is undertaken in Cologne to validate most of the concepts presented at the Preliminary Design Review. A core unit of the WCU is the integrating sphere combined with the black body, which is the hub delivering the calibration functionalities. We first report the measured spatial uniformity of the output port of the integrating sphere when fed with the black body source radiation. The measurement made using our uncooled thermal camera, evidences a spatial uniformity below 1% RMS. Longer integration times will further improve the final accuracy on this important parameter. We also take a closer look at the black body source and report on its flux temporal stability, which is found to be better than 1% over a 2h duration. We characterize time windows for different settings of the main WCU light source, which is the black body and stability and repeatability of the detected signal. Through different experiments we investigated the best options to manufacture the aperture mask that will be used to generate artificial point sources.

The warm calibration unit (WCU) is one subsystem of the future METIS instrument on the European Extremely Large Telescope (E-ELT). Operating at daytime temperature, the WCU is mounted above the main cryostat of METIS and will be employed as calibration reference for science observations, as well as for verification and alignment purposes during the AIT phase. The WCU is designed and constructed at the University of Cologne, partner in the METIS consortium. The WCU, together with the full METIS instrument, went recently through a successful preliminary design review (PDR) phase at ESO and is entering now the Phase C of the project. In this paper, we present the current status of the WCU and summarize the mostly mechanical and optical engineering work. We adopted a hexapod unit to interface with the METIS cryostat and a CFRP-based optical bench to optimally cope with alignment flexure. We develop the case for fiber-fed laser sources feeding the integrating sphere for spectral calibration of the LM-Spectrograph of METIS. We detail the activity foreseen for Phase C including the optical tolerances analysis, the eigenfrequency and earthquake analysis and a preparation of the sub-system MAIT work, finishing the paper with a short overview of the WCU future plans.

METIS is one of the first three instruments for the ELT, Europe’s next-generation ground-based telescope. It will offer imaging, coronagraphy and spectroscopy in the L, M and N bands for general-purpose science in astrophysics. Among its main science drivers are circumstellar disks and extrasolar planets observations, which requires demanding high contrast imaging techniques. In that framework, METIS will be equipped with state-of-the-art phase mask coronagraphs: Apodizing Phase Plate (APP) and Annular Grooves Phase Mask (AGPM). Manufacturing the AGPM coronagraphs is a complex process that requires performance assessment with specific testing before implementation into the instrument. At Department of Astrophysics (CEA Saclay, France), responsible for the testing of the N-band AGPMs, a previously available test bench with a telescope simulator and cryogenic facility has been upgraded to comply with the AGPM tests requirements. This paper presents these requirements and describes the test bench design adopted. Then, based on preliminary results, we discuss the original solutions that permitted to reach our goals.

Extremely Large Telescopes are considered worldwide as one of the highest priorities in ground-based astronomy, for they have the potential to vastly advance astrophysical knowledge with detailed studies of subjects including the first objects in the Universe, exoplanets, super-massive black holes, and the nature and distribution of the dark matter and dark energy which dominate the Universe. ESO is building its own Extremely Large optical/infrared Telescope, the ELT. This new telescope will have a 39 m main mirror and will be the largest optical/NIR telescope in the world, able to work at the diffraction limit. METIS, one of the first light instruments of the ELT, has powerful imaging and spectrographic capabilities on the thermal wavelengths. It will allow the investigation of key properties of a wide range of objects, from exoplanets to star forming regions, and it is highly complementary to other facilities such as the JWST. METIS is an extremely complex instrument, weighing almost 11 ton, and requiring high positioning and steering precisions. Here we present the ELT’s METIS’ Warm Support Structure. It consists on a 7 leg elevation platform, a passive hexapod capable of providing METIS with sub-millimetre and arcsecond positioning and steering resolutions, and an access platform where personnel can perform in-situ maintenance activities. The support structure weighs less than 5 ton and is capable of surviving earthquake conditions with accelerations up to 5g. The current design is supported by FEM simulations in ANSYS®, and was approved for Phase C.

The InfraRed Imaging Spectrograph (IRIS) is a first-light instrument for the Thirty Meter Telescope (TMT) that will be used to sample the corrected adaptive optics field by the Narrow-Field Infrared Adaptive Optics System (NFIRAOS) with a near-infrared (0.8 - 2.4 µm) imaging camera and integral field spectrograph. To better understand IRIS science specifications we use the IRIS data simulator to characterize relative photometric precision and accuracy across the IRIS imaging camera 34”x34” field of view. Because the Point Spread Function (PSF) varies due to the effects of anisoplanatism, we use the Anisoplanatic and Instrumental Reconstruction of Off-axis PSFs for AO (AIROPA) software package to conduct photometric measurements on simulated frames using PSF-fitting as the PSF varies in single-source, binary, and crowded field use cases. We report photometric performance of the imaging camera as a function of the instrumental noise properties including dark current and read noise. Using the same methods, we conduct comparisons of photometric performance with reconstructed PSFs, in order to test the veracity of the current PSF-Reconstruction algorithms for IRIS/TMT.

HARMONI, an adaptive optics (AO) assisted integral field spectrograph (IFS), will be the core spectroscopic capability for the European Southern Observatory’s (ESO’s) Extremely Large Telescope (ELT). It will support several AO modes and achieve diffraction-limited (≈10 mas) to seeing-limited spatial resolution, at low to high spectral resolving powers (λ/Δλ = 3,000-18,000) spanning the visible to near-infrared wavelength range (0.46-2.45 μm). In this paper we describe the modelling of the entire optical science path, from the creation of the end-to-end optical model, over how we analyse the optical performance, to the preliminary results of both nominal and as-built Monte-Carlo instances of HARMONI.

The paper reports an overview of the preliminary optical design for the MICADO Relay Optics (RO) to enable early science observations of the instrument at the Extremely Large Telescope (ELT) with single-conjugate adaptive optics (SCAO). MICADO, the Multi-AO Imaging Camera for Deep Observations, is a first light imager, astrometric camera and spectrograph operating between 0.8 µm and 2.4 µm. The RO are based on a six mirror (6M) optical assembly that relays the telescope focal plane to an accessible position for the MICADO cryostat. The system includes three powered mirrors in a three-mirror-anastigmat configuration and three piston and tip- tilt flat mirrors for the alignment and the beam folding at the interfaces with the ELT and MICADO. This design represents an interesting example of optical performance optimization to achieve high performances optics both for the direct imaging channel and the pupil interface towards MICADO and the SCAO. The RO performances are analyzed and verified at a design level showing the compliance with the requirement specifications and the reliability of the design is assessed with an extended tolerance study and a minimization of the vignetting factor at the MICADO cold stop. The manuscript also contains a demonstration of the optical alignability of a 6M system in terms of pupil and focal plane steering that are essential to cope with the interface tolerances of the next generation of instrument at the foci of the extremely large telescopes.

This paper provides a description of the Instrument Control Hardware design for MAORY (Multi-conjugate Adaptive Optics RelaY), a first light instrument for ESO ELT. The MAORY Instrument Control Hardware is in charge of the control electronics of the entire system. It comprises all the implemented electronic devices (power supplies, PLC CPUs and terminals, motor drivers, control panel, network switches, sensors) and the harness used to connect them. The instrument control system architecture is based on the use of PLC and EtherCAT fieldbus protocol, which allows for a distribution of PLC terminals controlled by the same CPU that do not have to be physically located in the same place to communicate among each other.

We introduce the Michigan Infrared Test Thermal ELT N-band (MITTEN) Cryostat, a new facility for testing infrared detectors with a focus on mid-infrared (MIR) wavelengths (8-13 microns). New generations of large format, deep well, fast readout MIR detectors are now becoming available to the astronomical community. As one example, Teledyne Imaging Sensors (TIS) has introduced a long-wave Mercury-Cadmium-Telluride (MCT) array, GeoSnap, with high quantum efficiency (< 65 %) and improved noise properties compared to previous generation Si:As blocked impurity band (BIB) detectors. GeoSnap promises improved sensitivities, and efficiencies, for future background-limited MIR instruments, in particular with future extremely large telescopes (ELTs). We describe our new test facility suitable for measuring characteristics of these detectors, such as read noise, dark current, linearity, gain, pixel operability, quantum efficiency, and point source imaging performance relative to a background scene, as well as multiple point sources of differing contrast. MITTEN has an internal light source, and soon an accompanying filter wheel and aperture plate, reimaged onto the detector using an Offner relay. The baseline temperature of the cryostat interior is maintained is < 40 K and the optical bench maintains a temperature of 16 K using a two-stage pulse-tube cryocooler package from Cryomech. No measurable background radiation from the cryostat interior has yet been detected.

Recent changes to the Montreal Protocol have led to the eventual phase-out of hydrofluorocarbon-based refrigerants due to their high global warming potential (GWP). TMT has thus transitioned from R507 (GWP ~ 3900) to CO2 (GWP =1) as the primary observatory supplied refrigerant. Thus, the cooling system for NFIRAOS (TMT’s first light adaptive optics system) was redesigned to work with this high pressure refrigerant. In this paper, we describe the key refrigeration requirements and present the updated design of the NFIRAOS cooling system, including its overall architecture, main components and safety related features. To de-risk aspects of the design and to assess vibration levels of the system (critical for the AO system performance) a prototype CO2 cooling system was built and characterized. Key measurement results are presented.

The CARMENES instrument consists of two cross-dispersed ´echelle spectrographs, which together cover the wavelength range from 5,200 to 17,100 ˚A. During its first five years of operation at the 3.5 m telescope on Calar Alto, Spain, it has been used for a radial-velocity survey of 365 M dwarfs, for follow-up radial-velocity observations of transiting exoplanets, and for spectroscopic studies of exoplanet atmospheres during transits. The CARMENES data have also yielded a wealth of information on the fundamental parameters and activity of M dwarfs. We provide an overview of the scientific results from the main CARMENES survey in the years 2016 to 2020.

We describe the performances of a novel Doppler imager, aimed to detect acoustic oscillations and atmospheric dynamics at the surface of giant planets of the Solar System in the frame of the JOVIAL (Jovian Oscillations detection by Velocity Imaging At several Longitudes) project. The first JOVIAL instrument was installed on the 188cm telescope at Okayama branch of National Astronomical Observatory of Japan (NAOJ) in April 2019. This instrument is a part of a ground based network of three identical instruments installed on telescopes around the world for continuous observations. First observations of Jupiter with the JOVIAL instrument were achieved in June 2019. We describe the instrument principle, its design and the set-up at Okayama observatory, as well as the performances reached during the first observing run. We finally provide plans for future observations with the network.

We are developing a high-resolution near-infrared spectrograph for exoplanet searches with telescopes in Suther- land, South Africa; the South Africa Near-infrared Doppler (SAND) instrument. It covers the z- and Y -bands (0.83–1.10 µm) simultaneously with a maximum spectral resolution of 55, 000. This specification enables the precise radial velocity (RV) measurements to search for both giant planets around young stars and habitable planets around nearby M-dwarfs. The SAND is a fiber-fed instrument and, therefore, can be installed into several telescopes at the same site by changing the fiber connection. It will be operated mainly on the PRIME telescope, which is newly developed by Osaka University in Japan. The InfraRed Survey Facility (IRSF) and the Southern African Large Telescope (SALT) are also candidate telescopes for the installation. Inside the SAND spectrograph, a star image ejected from the fiber is sliced half and each sliced image is spectrally dispersed by an echelle grating. As a reference source for the wavelength calibration, light transmitted from a Fabry-Perot Etalon is simultaneously injected into the spectrograph and share the almost identical optical pass. The SAND is expected to realize RV-measurements for targets in large stellar associations at the southern sky, with exclusive and flexible use of the telescope time.

ESPRESSO is a high resolution, super stable fiber-fed echelle spectrograph, installed at the ESO-VLT Combined Coudé Laboratory of the Paranal Observatory. The main instrument subsystems are: Coudé Path, Fiber Link (FL) and Spectrograph. After installation and verification, the FL subsystem flux efficiency did not fully meet the requirements. We describe the FL subsystem upgrade, required in order to improve the optical efficiency and to meet the throughput specifications. We present the opto-mechanical design improvements, aimed to ensure proper reliability and stability of the FL subsystem both in the alignment phase and in the integration on the spectrograph. Moreover, we summarize the activities done for the different units along the upgrade phases: AIT in laboratory, FL subsystem integration on the spectrograph at VLT and on-site efficiency verifications. Measurements done before and during instrument re- commissioning show a throughput improvement of more than 30%.

The Manfred Hirt Planet Spectrograph (MaHPS) — formerly also referred to as FOCES — is a high-resolution echelle spectrograph at the 2m telescope of the Wendelstein Observatory. One of its main scientific goals is the detection of planets at the few m/s level. To achieve such high precisions on a long-term scale, environmental stabilization of the instrument is required. The currently used temperature and pressure control systems are introduced and we present two different temperature control setups, with two and three actively controlled layers respectively. A series of measurements with an Astro Frequency Comb (AFC) as calibrator is shown to illustrate the system performance.

Since the first discovery of a planet outside of our Solar System in 1995, exoplanet research has shifted from detecting to characterizing worlds around other stars. The TESS (NASA, launched 2019) and PLATO mission (ESA, planned launch 2026) will find and constrain the size of thousands of exoplanets around bright stars all over the sky. Radial velocity measurements are needed to characterize the orbit and mass, and complete the picture of densities and composition of the exoplanet systems found. The Ariel mission (ESA, planned launch 2028) will characterize exoplanet atmospheres with infrared spectroscopy. Characterization of stellar activity using optical spectroscopy from the ground is key to retrieve the spectral footprint of the planetary atmosphere in Ariel’s spectra. To enable the scientific harvest of the TESS, PLATO and Ariel space missions, we plan to install MARVEL as an extension of the existing Mercator Telescope at the Roque De Los Muchachos Observatory on La Palma (SPAIN). MARVEL consists of an array of four 80 cm telescopes linked through optical fibers to a single high-resolution echelle spectrograph, optimized for extreme-precision radial velocity measurements. It can observe the radial velocities of four different stars simultaneously or, alternatively, combine the flux from four telescopes pointing to a single faint target in one spectrum. MARVEL is constructed by a KU Leuven (Belgium) led collaboration, with contributions from the UK, Austria, Australia, Sweden, Denmark and Spain. In this paper, we present the MARVEL instrument with special focus on the optical design and expected performance of the spectrograph, and report on the status of the project.

NEID is a radial velocity (RV) instrument including an ultra-stabilized fiber-fed spectrograph, installed in 2019 at the 3.5m WIYN telescope at Kitt Peak National Observatory. Accompanying it is a solar feed system built to supply the spectrograph with disk-integrated sunlight. Observing the Sun “as a star” is essential for developing and validating mitigation strategies for RV variations due to stellar activity and instrument systematics, thus enabling more-effective detections of lower-mass exoplanets. In this paper, we will detail the design of the NEID solar feed system and showcase early results addressing NEID systematics and solar RV variability.

The Macquarie University campus observatory has recently undergone a significant upgrade, with a new fully- automated 0.6 m telescope and on-site facilities including an instrumentation laboratory. Here we report on the design, assembly, and first on-sky tests of a new high-resolution echelle spectrograph for the observatory. This spectrograph will be a key resource at our campus observatory, providing high fidelity measurements that will enable future research, in particular Master and PhD theses that require stellar spectroscopy or radial velocity measurements. The instrument will also form a cornerstone of the laboratory components of the undergraduate astronomy degree, and together with the new 0.6 m telescope, a key tool for project-based learning at the campus observatory. The instrument has been developed with radial velocity precision as the driving metric, and with future work on the environmental stabilisation it is expected to reach a radial velocity precision of 3 m s⁻¹, enabling the observation of a wide range of exoplanets.

Fourier Transform Spectrographs (FTS) are versatile tools for measuring accurate, high resolution spectra. They are internally calibrated by a reference laser that runs in parallel to the science light. Therefore it is crucial to properly align these two beams with respect to each other. We show how this can be achieved by feeding a part of the reference light into the optical path of the science beam. For astronomical applications it’s often useful to use optical fibers. We present a coupling setup for our Bruker Optics IFS 125 FTS, consisting of (1) two hexagonal input fibers, (2) dichroic beam-combining for measuring two light sources simultaneously and (3) optimized optics to match the original Bruker design. The hexagonal shape of the fiber cores secures sufficient mode scrambling inside the fibers, resulting in constant beam parameters and a more homogeneous illumination of the entrance aperture of the FTS.

The Gemini High-Resolution Optical SpecTrograph (GHOST) is the newest instrument being integrated for the Gemini telescopes, in a collaboration between the Australian National University (ANU), the NRC-Herzberg in Canada and the Australian Astronomical Observatory (AAO). The GHOST outer enclosure consists of 20 heated thermal panels, forming an encompassing structure with a stationary ‘bridge’ assembly and two removable sections for access. The outer enclosure provides an ultra-stable, dark environment for the bench spectrograph. This paper reviews the outer enclosure construction from a practical standpoint, examining how environmental requirements are met through the thermal panel construction, light seal and dry air system designs. This paper also describes thermal panel production workflow, enclosure assembly methodology, alignment and cable routing challenges. Results of the enclosure's thermal stability verification tests are presented and a list of lessons learned.

The ESPRESSO spectrograph is a high resolution, super stable echelle cross-dispersed fiber-fed spectrograph, installed in the ESO-VLT Combined Coudé Laboratory of the ESO-VLT in Cerro Paranal. In the framework of the Fiber-Link (FL) recovery project, which was necessary to meet the throughput requirement of the instrument, we redesigned and build the whole fiber bundle. The FL subsystem of ESPRESSO is composed by the input ends, one per telescope and observing mode, which inject the telescope light into the fibers, the double scrambler, the light combiner for the multi-telescope mode, and the spectrograph entrance slit. In this paper we focus on the details of the optical design of the scrambler and the beam combiner, redesigned to ensure proper transmission in the blue, and on the mechanical design of the input ends and the scrambler, aimed to ensure proper reliability, alignment accuracy, stability, and robustness of the scrambler, both in the alignment phase and during the integration in the spectrograph at the telescope.

Laser frequency combs are an ideal calibration source for precision astronomical spectrographs. We report on the demonstrated long term operation of a laser frequency comb that we designed and built as the primary calibrator for the Habitable Zone Planet Finder (HPF). The core technology of the comb is based on robust, polarization maintaining fiber coupled electro-optic modulators and broadband supercontinuum generation spanning 700-1600 nm in an efficient silicon nitride waveguide. The comb is continuously maintained on and ready to use, and since May 2018 the laser frequency comb has had a total uptime of 97%.

NIRPS is a near-infrared RV spectrograph for ESO 3.6m telescope in La Silla. At the present the instrument is in the integration phase. This new instrument will be covering YJH bands to detect and characterize low-mass planets in the habitable zone of M dwarfs, and will allow RV measurements at 1 m/s level, at 100K spectral resolution. The instrument consists of three subsystems: the front-end extracts the 700nm-2400nm band from the telescope beam, fiber link scrambles and guides light into the spectrograph, and the spectrograph itself. The cryogenic spectrograph unit, is operating at 80 K. Among key parameters is thermal stability of less than 1 mK over 24 hours. In this paper we describe as-built thermal and vacuum system design, work performed on assembly and integration of the cryo-vacuum subsystem, and validation of the thermal design, and thermal stability.

Using laser heterodyne radiometry with a resolution of 100 MHz we have observed a selection of iron lines in the solar spectrum near 1565 nm with an approximate resolving power of 2,000,000 million. With a laser frequency comb as the wavelength calibration source we have achieved absolute frequency instability on measurements of single lines at better than 13 MHz in a 10 second averaging window, and SNR of over 5000 when averaging up to a 1 hour exposure. An amplitude servo on the laser power creates a stable, repeatable background level, allowing for simple extraction of the line depth.

The NEID spectrograph is a R ~ 120,000 resolution fiber-fed and highly stabilized spectrograph for extreme radial velocity (RV) precision. It is being commissioned at the 3.5 m WIYN telescope in Kitt Peak National Observatory with a desired instrumental precision of better than 30 cm s⁻¹. NEID’s bandpass of 380 – 930 nm enables the simultaneous wavelength coverage of activity indicators from the Ca HK lines in the blue to the Ca IR triplet in the IR. In this paper we will present our efforts to characterize and mitigate optical ghosts in the NEID spectrograph during assembly, integration and testing, and highlight several of the dominant optical element contributors such as the cross dispersion prism and input optics. We shall present simulations of the 2-D spectrum and discuss the predicted ghost features on the focal plane, and how they may impact the RV performance for NEID. We also present the mitigation strategy adopted for each ghost which may be applied to future instrument designs. This work will enable other instrument builders to potentially avoid some of these issues, as well as outline mitigation strategies.

The NEID extreme precision radial velocity spectrometer is being commissioned at the WIYN 3.5 meter telescope, Kitt Peak National Observatory, Tucson Arizona. In order to meet the stringent 27 cm per second radial velocity precision, the light to NEID comes from an extremely stable fiber feed, called the NEID Port Adapter, equipped with fast tip-tilt correction. The WIYN telescope vibration environment and the Port Adapter tip-tilt and guiding system are key to achieving the 50 milliarcsecond-level centroiding stability required. Here we describe the servo system performance, along with vibration analysis and mitigation plans. This work would be relevant to upgrade and retrofit efforts as older observatories incorporate low-order wavefront correction to stabilize light to advanced spectrometers and imagers.

The Keck Planet Finder (KPF) is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. KPF is designed to characterize exoplanets via Doppler spectroscopy with a goal of a single measurement precision of 0.3 m s^-1 or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. Here we provide post-preliminary design review design updates for several subsystems, including: the main spectrometer, the fabrication of the Zerodur optical bench; the data reduction pipeline; fiber agitator; fiber cable design; fiber scrambler; VPH testing results and the exposure meter.

The instrument group of the Herzberg Astronomy and Astrophysics has been subcontracted by Australian Astronomical Optics (AAO) at Macquarie University to design and build the bench spectrograph for the Gemini High-Resolution Optical SpecTrograph (GHOST) instrument. The GHOST instrument is being developed for the Gemini telescope and is a collaboration between AAO, the Herzberg Astronomy and Astrophysics (HAA) in Canada and the Australian National University (ANU). The instrument is a fiber fed spectrograph with R<50,000 in two-object mode and R<75,000 in single object mode. This paper presents the i ph and the performance results for the laboratory testing of the spectrograph.

We develop an interferometer for measurement of narrow atmospheric spectral lines, mainly in the infra-red. The bias and background are dominant, but irrelevant for the measurement. Hence we employ an optical band-pass filter tuned to the expected width of the spectral lines: Instead of scanning the full path delay with a single detector, we image the fringes on a two-dimensional camera. Applications are for search for life on exoplanets, and for our own atmosphere

We describe efforts to equip the Southern African Large Telescope (SALT) for precision radial velocity (PRV) work. Our current focus is on commissioning the high-stability (HS) mode of the High-Resolution Spectrograph (HRS), the mode intended to support exoplanet science. After replacing the original commercial iodine cell with a custom-built, precisely characterised one and following established best practice in terms of observing strategy and data reduction, this system now delivers 3-4 m/s radial velocity stability on 5th and 6th magnitude stars. Unfortunately, the throughput is compromised by the HRS dichroic split being at 555 nm (i.e. roughly midway through the 100 nm span of the iodine absorption spectrum). Furthermore, SALT’s fixed elevation axis limits the exposure time available for a given target and hence the depth and/or precision achievable with the iodine cell. The HS mode’s simultaneous ThAr option uses the full 370–890 nm passband of the HRS and does not suffer gas cell absorption losses, so it may be more suitable for exoplanet work. The first step was to quantify the internal stability of the spectrograph, which requires simultaneously injecting arc light into the object and calibration fibres. The HS mode’s optical feed was modified accordingly, stability test runs were conducted and the necessary analysis tools were developed. The initial stability test yielded encouraging results and though more testing is still to be done, SAL a laser frequency comb to support the development of HRS PRV capability.

For on the order of a thousand dollars, we designed and built a high-resolution (R~19,000) optical spectrograph covering 400-950nm, designed to observe bright targets with small telescopes. Innovative 3D printing methods allow us to accurately and cheaply mount and house inexpensive commercial-off-the-shelf (COTS) optical components, including a DSLR camera lens. Bifrost is a fiber-fed spectrograph compatible with our existing and similarly inexpensive 3D-printed acquisition/guide system (compatible with a number of small telescopes, including the Meade LX200 series). A high resolution spectrograph with broadband coverage on a small telescope is optimal for cadence-sensitive spectroscopic variables; our targets of interest include high-mass X-ray binaries, ultra-magnetic stars, and the jets of the microquasar SS 433.

Precision Doppler spectroscopy serves as an important tool for Radial Velocity (RV) measurements by observing Doppler shift in the stellar spectrum, which are used for various applications. Passively stabilized Fabry-Perot (FP) etalon based wavelength calibration is one of the techniques used for Doppler spectroscopy. The FP is kept in a pressure and temperature-stabilized environment for it to produce equispaced transmission lines. Since the FP is stable and the line shape is invariant across wavelength pass band, they can be used to determine the spectrograph’s instrumental artifacts and hence analyze spectrograph performance. Knowledge of instrument effects also helps in better prediction of the wavelength calibration model for the spectrograph. We have tested a passively stabilized FP on Vainu Bappu Telescope (VBT) Echelle spectrograph and Hanle Echelle spectrograph (HESP) and observed field curvature and distortion in both. We are analyzing the artifacts introduced and correcting for the same using image processing methods to compensate for the same in wavelength calibration model developed for the FP-based calibrator.

In October 2019, the NEID instrument (PI Suvrath Mahadevan, PSU) was delivered to the WIYN 3.5 m Telescope at Kitt Peak National Observatory. Commissioning began shortly after delivery, but was paused due to a COVID-19 imposed observatory shutdown in March 2020. The observatory has recently reopened and NEID commissioning has resumed. NEID is an optical (380-930 nm), fiber-fed, precision Doppler radial velocity system developed as part of the NN-EXPLORE partnership. While the spectrometer and calibration system are maintained in a highly controlled environment on the basement level of the WIYN, the NEID Port Adapter mounts directly to a bent-Cassegrain port on the telescope and is responsible for precisely and stably placing target light on the science fibers. Here we present a brief overview of the as-built Port Adapter and its sub-components. We then discuss preliminary on-sky performance compared to requirements as well as next steps as we complete commissioning.

Small diameter single-mode fiber (SMF) allows for the design of compact spectrographs that operate at the diffraction limit. The small instrument scale, in turn, allows cost-effective configuration flexibility to use the instrument as a testbed for infrared SMF spectrograph technologies. The same base instrument could be coupled to different adaptive optics (AO) and non-AO SMF feeds. We present the build for such a spectrograph, Iranti, which works in the near-infrared (NIR) range and incorporates novel techniques. Our implementation of this instrument has sufficient cross dispersion to allow testing of a range of input fiber links, including multiple fibers or multi-core fibers (MCFs); the camera optics and detector can also be swapped out easily for different wavelength ranges. The base system uses a white pupil design that relays a slow beam between the collimator, an R6 echelle grating with 13.33 lines/mm and a volume phase holographic grating (VPH) as a cross disperser. In Iranti, we also address mechanical and thermal considerations to improve stability in the instrument. We configure the instrument for ranges in 800 to 1300 nm and characterize system efficiency and stability.

The ESPRESSO spectrograph is a high resolution, super stable echelle cross-dispersed fibre-fed spectrograph, installed in the ESO-VLT Combined Coudé Laboratory of the ESO-VLT in Cerro Paranal. In the framework of the Fiber-Link (FL) recovery project, which was necessary to meet the throughput requirement of the instrument, we redesigned and build the whole fibre bundle. The FL subsystem of ESPRESSO is composed by the Input Ends (IE), one per telescope and observing mode, which inject the telescope light into the fibres, the double scrambler and the light combiner for the multi-telescope mode, which merges the light of the four telescopes in a single fibre, and the spectrograph entrance slit. In this paper we focus on the alignment strategy, the tools developed and the activities performed to integrate the different components of the FL. We will describe the gluing system of the mini-lenses on the fibre ends, to guarantee the field and pupil centration; the integration of the IE, where the position and telecentricity of the two channels (star/sky) were necessary to meet the interface with the telescopes; and the integration of the beam combiner for the multi-telescope mode, particularly demanding for the small scale of the elements to integrate and the high accuracy required to guarantee the high throughput. We will also show the procedure for the scrambler alignment for the single telescope modes and the multi- telescope mode developed in laboratory and replicated at the telescope.

Detection of exoplanets using high-resolution spectroscopy is limited by a balance between spatial and spectral sampling and resolution. We propose to use a highly multiplexed Bragg grating (HMBG) to optically correlate relevant parts of a spectrum. The HMBG sidesteps the trade-off between spatial and spectral resolution, increasing the number of available spatial pixels by 10^3-10^4. The HMBG is implemented using an acousto-optical filter. This filter gives the freedom to dynamically combine any desired set of spectral lines. We will show the simulated performance of a system with an HMBG in a realistic environment.

The Manfred Hirt Planet Spectrograph - formerly operated under the name FOCES - started its regular scientific observation program in fall 2019 at the 2m telescope of the Wendelstein Observatory, operated by the University Observatory of the LMU Munich. We present the first radial velocity stability measurements of an astronomical target, the 51 Pegasi b exoplanet system, utilizing our Astro Frequency Comb (ACF) for wavelength calibration. For computing RV shifts from orderwisely extracted Echelle spectra we have developed a new software pipeline. In this proceeding we will introduce the most important features of our pipeline: wavelength calibration with simultaneously recorded spectra of the AFC, generation of spectral templates, and an optional fit or cross- correlation function (CCF) for the calculation of the relative RV signals. Finally, the performance of the pipeline real data is demonstrated.

NEID is a high resolution echelle spectrograph designed to enable extremely precise Doppler radial velocity observations of stars in the 380-930nm wavelength range1. It has recently been installed at the 3.5m WIYN telescope at Kitt Peak National Observatory, and is currently being commissioned. The design is based on a white pupil layout with a monolithic parabolic primary mirror and a 195mm pupil size on the R4 Echelle grating. Here we describe the optical and mechanical design, assembly, and alignment of the fiber injection system which converts the native focal ratio of the sky, calibration, and science fibers to the focal ratio required to form the 195mm collimated beam.

SHARK-NIR is a coronagraphic camera with spectroscopic capabilities for the Large Binocular Telescope (LBT) currently in its AIV phase, and operates in the near-infrared regime between 0.96 µm to 1.7 µm. We describe the test bench for analyzing and integrating the coronagraphic masks, by reproducing the focal plane scale, the entrance pupil dimension, and the coronagraphic techniques as similar as possible to the final assembly. The alignment procedures and code developed in Python language evaluates if these methods are accurate enough to reach the design tolerances and contrast requirements.

Subaru telescope has been operating a high-contrast imaging instruments called Subaru coronagraphic extreme adaptive optics (SCExAO) which is used for exoplanet research. We are developing phase mask coronagraphs using photonic crystal wave plates inside the SCExAO. An eight-octant phase mask (8OPM) of three-layer achromatic structure has been fabricated as a second generation. It was designed for J and H band to reach 10^-5 contrast, and Ks band to 10^-4. A retardation and a coronagraphic performance of the 8OPM were confirmed almost as designed at 1550nm. An apodised (binary shaped) pupil to be used with the 8OPM was also studied to suppress diffracted light by the secondary shadow and spiders. We confirmed a performance of the combination of the apodizer and the 8OPM at visible wavelengths in a lab. We optimized the apodizer for a pupil of the SCExAO where we obtained a transmission of 50 % and a contrast of 10^-4 the center and 10^-6 at outer region. We manufactured the designed apodizer to be installed in SCExAO for infrared observations.

The Keck Planet Imager and Characterizer (KPIC) is a purpose-built instrument for high-dispersion coronagraphy in the K and L bands on Keck. This instrument will provide the first high resolution (R>30,000) spectra of known directly imaged exoplanets and low-mass brown dwarf companions visible in the northern hemisphere. KPIC is developed in phases. Phase I is currently at Keck in the early operations stage, and the phase II upgrade will deploy in late 2021. The goal of phase II is to maximize the throughput for planet light and minimize the stellar leakage, hence reducing the exposure time needed to acquire spectra with a given signal-to- noise ratio. To achieve this, KPIC phase II exploits several innovative technologies that have not been combined this way before. These include a 1000-element deformable mirror for wavefront correction and speckle control, a set of lossless beam shaping optics to maximize coupling into the fiber, a pupil apodizer to suppress unwanted starlight, a pupil plane vortex mask to enable the acquisition of spectra at and within the diffraction limit, and an atmospheric dispersion compensator. These modules, when combined with the active fiber injection unit present in phase I, will make for a highly efficient exoplanet characterization platform. In this paper, we will present the final design of the optics and opto-mechanics and highlight some innovative solutions we implemented to facilitate all the new capabilities. We will provide an overview of the assembly and laboratory testing of the sub-modules and some of the results. Finally, we will outline the deployment timeline.

Liger is a next-generation near-infrared imager and integral field spectrograph (IFS) for the W.M. Keck Obser- vatory designed to take advantage of the Keck All-Sky Precision Adaptive Optics (KAPA) upgrade. Liger will operate at spectral resolving powers between R~4,000 - 10,000 over a wavelength range of 0.8-2.4µm. Liger takes advantage of a sequential imager and spectrograph design that allows for simultaneous observations between the two channels using the same filter wheel and cold pupil stop. We present the design for the filter wheels and pupil mask and their location and tolerances in the optical design. The filter mechanism is a multi-wheel de- sign drawing from the heritage of the current Keck/OSIRIS imager single wheel design. The Liger multi-wheel configuration is designed to allow future upgrades to the number and range of filters throughout the life of the instrument. The pupil mechanism is designed to be similarly upgradeable with the option to add multiple pupil mask options. A smaller wheel mechanism allows the user to select the desired pupil mask with open slots being designed in for future upgrade capabilities. An ideal pupil would match the shape of the image formed of the primary and would track its rotation. For different pupil shapes without tracking we model the additional exposure time needed to achieve the same signal to noise of an ideal pupil and determine that a set of fixed masks of different shapes provides a mechanically simpler system with little compromise in performance.

We present end-to-end simulations of SCALES, the third generation thermal-infrared diffraction limited imager and low/med-resolution integral field spectrograph (IFS) being designed for Keck. The 2-5 micron sensitivity of SCALES enables detection and characterization of a wide variety of exoplanets, including exoplanets detected through long-baseline astrometry, radial-velocity planets on wide orbits, accreting protoplanets in nearby starforming regions, and reflected-light planets around the nearest stars. The simulation goal is to generate high-fidelity mock data to assess the scientific capabilities of the SCALES instrument at current and future design stages. The simulation processes arbitrary-resolution input intensity fields with a proposed observation pattern into an entire mock dataset of raw detector read-out lenslet-based IFS frames with calibrations and metadata, which are then reduced by the IFS data reduction pipeline to be analyzed by the user.

SHARK-NIR is a high contrast camera for the LBT, working in Y, J and H bands. It has been conceived and designed to fully exploit the high Strehl adaptive optics correction delivered by the FLAO module, which is being upgraded to SOUL, and will implement different coronagraphic techniques, with contrast as high as 10^-6 up to 65 mas from the star. To maximize the achievable contrast, SHARK-NIR has a couple of peculiar features, namely a fast internal TT loop to minimize the residual jitter and a local NCPA correction, performed through a DM inside the instrument itself. Other than high-contrast imaging, SHARK-NIR also has spectroscopic capabilities, with low and medium resolution, and its relatively wide Field of View (18 x 18 arcsec) makes it accessible to other scientific targets, such as galactic jets and disks, as well as extra-galactic cases. Sharing the focal station with another instrument at LBT (LBTI), the design has been kept very compact. This has been achieved through the use of 4 Off-Axis Parabolic mirrors (OAPs) and three flat folding mirrors able to provide two pupil planes and two focal planes required by the coronagraphic techniques implemented. A mixed optical-mechanical alignment procedure has been identified and extensively simulated using ray-tracing software, demonstrating that the proposed technique converges to the required performance. We report here about the SHARK-NIR lesson learned and status in the frame of the Assembly, Integration and Verification phase (AIV), delayed due to the covid 19 emergency, which is going to finish in first half of 2021 and bringing in this way the first photons to the instrument by the end of 2021.

SPEED – the segmented pupil experiment for exoplanet detection – currently in final integration phase, is designed to test strategies and technologies for high-contrast instrumentation with segmented telescopes by offering an ideal cocoon to progress in these domains with complex telescope apertures. SPEED combines precision segment phasing architectures, optimised small inner-working angle (IWA) coronagraphy, and wavefront shaping to create a small IWA and small field of view (FoV) dark hole in the science detector. Over the years SPEED has made significant hardware and software progress to start the exploitation of the bench. We have completed several key hardware including the common-path wavefront sensor for cophasing optics based on the self-coherent camera (SCC) concept. In this paper, we report on the wavefront sensing strategy designed for SPEED, from the adaptation of the SCC concept to cophasing optics towards an alternative implementation of the conventional SCC, called the fast-modulated SCC, for both wavefront control and shaping applications. We present a progress overview on this wavefront sensor for (i) cophasing control and monitoring from the scientific image, as well as (ii) its interest for the wavefront shaping unit of the bench.

Phase diversity is a wavefront sensing technique that makes use of images in the scientific channel to derive the instrumental aberrations. Two images of whatever object are required, with a well-calibrated differential aberration (typically a pure defocus) between the two. We present here the laboratory demonstration of this concept in the specific context of SHARK-NIR, the new-generation high contrast imager for the Large Binocular Telescope. We investigated the behavior of the sensor in presence of several aberrations of variable amplitude and we optimized the retrieval algorithm parameters by comparing the results with the ones of a Shack-Hartmann sensor. We illustrate the challenges and the perspectives of this technique in view of its application to sense non-common path aberrations in SHARK-NIR.

Differential atmospheric refraction (DAR) limits the amount of light that can be coupled into a single mode fiber and provides additional complications for any fiber tracking system. We present an atmospheric dispersion corrector (ADC) design based off of two counter-rotating prisms to fit the needs of exoplanet spectroscopy for the Keck Planet Imager and Characterizer (KPIC) from 1.1 to 4.2 microns. Due to strong telluric effects, we find that the default Zemax prescription for DAR between 2 and 4.2 microns to be inaccurate up to 15 mas when comparing against DAR models computed from first principles. Using first-principle models, we developed our own custom ADC optimization solution and achieve less than 4 mas residual dispersion in any individual science band (J, K, L) down to 60 degree zenith angles, while the whole time maintaining less than 3 mas of residual dispersion in the tracking band (H) and less than 2 mas of residual dispersion between the tracking and science bands.

"The MCAO Assisted Visible Imager and Spectrograph (MAVIS), is a new instrument for ESO’s Very Large Telescope. The science instruments, namely an imager and a spectrograph observing at VIS wavelengths (370-1000nm), are fed by a MCAO module which performs wide field wavefront sensing and correction by means of both NGS and LGS stars. To maximize sky coverage, tip-tilt sensing is done at NIR wavelengths (1000-1700 nm) by selecting up to three stars in a 2arcmin FoV. In order to maximize the stability between NGS wavefront sensor and scientific instruments, we designed a common-path Atmospheric Dispersion Corrector (ADC) able to efficiently compensate for atmospheric differential refraction in the full wavelength range used by the MAVIS sub-systems. In this paper we present the design of the ADC. A few possible combinations of glasses are proposed and compared in terms of residual chromatic aberration, throughput, exit pupil movement and total thickness of the prism assembly."

"We present initial results from the Multi-conjugate Adaptive-optics Visible Imager-Spectrograph Image Simulator (MAVISIM) to explore the astrometric capabilities of the next generation instrument MAVIS. A core scientific and operational requirement of MAVIS will be to achieve highly accurate differential astrometry, with accuracies on the order that of the extremely large telescopes. To better understand the impact of known and anticipated astrometric error terms, we have created an initial astrometric budget which we present here to motivate the creation of MAVISIM. In this first version of MAVISIM we include three major astrometric error sources; point spread function (PSF) field variability due to high order aberrations, PSF degradation and field variability due to tip-tilt residual error, and field distortions due to non-common path aberrations in the AO module. An overview of MAVISIM is provided along with initial results from a study using MAVISIM to simulate an image of a Milky Way-like globular cluster. Astrometric accuracies are extracted using PSF-fitting photometry with encouraging results that suggest MAVIS will deliver accuracies of 150µas down to faint magnitudes."

Liger is a next generation adaptive optics (AO) fed integral field spectrograph (IFS) and imager for the W. M. Keck Observatory. This new instrument is being designed to take advantage of the upgraded AO system provided by Keck All-Sky Precision Adaptive-optics (KAPA). Liger will provide higher spectral resolving power (R~4,000- 10,000), wider wavelength coverage ( 0.8-2.4 µm), and larger fields of view than any current IFS. We present the design and analysis for a custom-made dewar chamber for characterizing the Liger opto-mechanical system. This dewar chamber is designed to test and assemble the Liger imaging camera and slicer IFS components while being adaptable for future experiments. The vacuum chamber will operate below 10⁻⁵ Torr with a cold shield that will be kept below 90 K. The dewar test chamber will be mounted to an optical vibration isolation platform and further isolated from the cryogenic and vacuum systems with bellows. The cold head and vacuums will be mounted to a custom cart that will also house the electronics and computer that interface with the experiment. This test chamber will provide an efficient means of calibrating and characterizing the Liger instrument and performing future experiments.

Because of bright starlight leakage in coronagraphic raw images, faint astrophysical objects such as exoplanets can only be detected using powerful point spread function (PSF) subtraction algorithms. However, these algorithms have strong effects on faint objects of interest, and often prevent precise spectroscopic analysis and scattering property measurements of circumstellar disks. For this reason, PSF-subtraction effects is currently the main limitations to the precise characterization of exoplanetary dust with scattered-light imaging. Forward modeling techniques have long been developed for point source objects (Pueyo 2016). However, Forward Modeling with disks is complicated by the fact that the disk cannot be simplified using a simple point source convolved by the PSF as the astrophysical model; all hypothetical disk morphologies must be explored to understand the subtle and non-linear effects of the PSF subtraction algorithm on the shape and local geometry of these systems. Because of their complex geometries, the forward-modeling process has to be repeated tens or hundred of thousands of times on disks with slightly different physical properties. All of these geometries are then compared to the PSF-subtracted image of the data, within an MCMC or a Chi-square wrapper. In this paper, we present here DiskFM, a new open-source algorithm included in the PSF subtraction algo- rithms package pyKLIP. This code allows to produce fast forward-modeling for a variety of observation strategies (ADI, SDI, ADI+SDI, RDI). pyKLIP has already been used for SPHERE/IRDIS and GPI data. It is readily available on all instruments supported by pyKLIP (SPHERE/IFS, SCExAO/CHARIS), and can be quickly adapted for other coronagraphic instruments.

The Gemini Planet Imager (GPI) is a high-contrast adaptive optics instrument designed to detect and characterize substellar companions and circumstellar debris disks around nearby young stars using infrared integral field spectroscopy and polarimetry. GPI has been in routine operations at Gemini South for the past six years. Because precise astrometry and photometry of exoplanets is critical to GPI's science, we undertook extensive efforts both in-lab and on-sky to refine the astrometric and photometric calibration of the instrument. We describe revisions to the GPI Data Reduction Pipeline (DRP) that account for these revised calibrations, and that fix several issues identified over the previous six years, including some subtle issues affecting astrometric calibrations caused by a drift of the instrument’s clock. These calibrations are critical for the interpretation of observations obtained with GPI, and for a comparison with measurements from other high-contrast imaging instruments.

SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS’ optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instruments. We present a comprehensive and detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument, using measurements with the internal source and observations of standard stars. The 22 wavelength bins of CHARIS provide a unique opportunity to investigate in detail the wavelength dependence of the instrumental polarization effects. We find that the image derotator (K-mirror) produces strongly wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. We fit the crosstalk of the half-wave plate (HWP) for all wavelengths with a simple two-parameter model of an achromatic HWP consisting of a layer of quartz and a layer of MgF2. While the magnitude of the telescope-induced polarization varies with wavelength, its angle varies solely with the altitude angle of the telescope. We show initial steps toward correcting on-sky data for the instrumental polarization effects, with which we aim to achieve a polarimetric accuracy <0.1% in the degree of linear polarization. Our calibrations of CHARIS’ spectropolarimetric mode enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions.

The Gemini Planet Imager (GPI) is a high-contrast imaging instrument designed to directly image and characterize exoplanets. GPI is currently undergoing several upgrades to improve performance. In this paper, we discuss the upgrades to the GPI IFS. This primarily focuses on the design and performance improvements of new prisms and filters. This includes an improved high-resolution prism which will provide more evenly dispersed spectra across y, J, H and K-bands. Additionally, we discuss the design and implementation of a new low-resolution mode and prism which allow for imaging of all four bands (y, J, H and K-bands) simultaneously at R≈10. We explore the possibility of using a multiband filter which would block the light between the four spectral bands. We discuss possible performance improvements from the multiband filter, if implemented. Finally we explore the possibility of making small changes to the optical design to improve the IFS’s performance near the edge of the field of view.

WALOP (Wide-Area Linear Optical Polarimeter)-South, to be mounted on the 1m SAAO telescope in South Africa, is first of the two WALOP instruments currently under development for carrying out the PASIPHAE survey. Scheduled for commissioning in the year 2021, the WALOP instruments will be used to measure the linear polarization of around 10⁶ stars in the SDSS-r broadband with 0.1 % polarimetric accuracy, covering 4000 square degrees in the Galactic polar regions. The combined capabilities of one-shot linear polarimetry, high polarimetric accuracy (< 0.1 %) and polarimetric sensitivity (< 0.05 %), and a large field of view (FOV) of 35 35 arcminutes make WALOP-South a unique astronomical instrument. In a single exposure, it is designed to measure the Stokes parameters I, q and u in the SDSS-r broadband and narrowband filters between 500-700 nm. During each measurement, four images of the full field corresponding to the polarization angles of 0°, 45°, 90° and 135° will be imaged on four detectors and carrying out differential photometry on these images will yield the Stokes parameters. Major challenges in designing WALOP-South instrument include- (a) in the optical design, correcting for the spectral dispersion introduced by large split angle Wollaston Prisms used as polarization analyzers as well as aberrations from the wide field, and (b) making an optomechanical design adherent to the tolerances required to obtain good imaging and polarimetric performance under all temperature conditions as well as telescope pointing positions. We present the optical and optomechanical design for WALOP-South which overcomes these challenges.

SOXS (Son Of X-Shooter) is the new medium resolution wide-band spectrograph to be installed at the 3.6m New Technology Telescope (NTT) in La Silla. SOXS will offer simultaneous wavelength coverage from 0.35 to 2.0 μm and will be dedicated to the study of transient and variable sources. While nominal optical performances of the system were presented in previous proceedings (Zanmar Sanchez et al. 2018), we here present a set of further analyses aimed to identify and quantify optical effects, due to changes in temperature and orientation of the instrument during alignment and operations.

The Simultaneous-color Wide-field Infrared Multi-object Spectrograph (SWIMS) is one of the 1st generation facility instruments for the University of Tokyo Atacama Observatory (TAO) 6.5 m telescope currently being constructed at the summit of Cerro Chajnantor (5,640 m altitude) in northern Chile. SWIMS has two optical arms, the blue arm covering 0.9–1.4 µm and the red 1.4–2.5 µm, by inserting a dichroic mirror into the collimated beam, and thus is capable of taking images in two filter-bands simultaneously in imaging mode, or whole nearinfrared (0.9–2.5 µm) low-to-medium resolution multi-object spectra in spectroscopy (MOS) mode, both with a single exposure. SWIMS was carried into Subaru Telescope in 2017 for performance evaluation prior to completion of the construction of the 6.5 m telescope, and successfully saw the imaging first light in May 2018 and MOS first light in Jan 2019. After three engineering runs including the first light observations, SWIMS has been accepted as a new PI instrument for Subaru Telescope from the semester S21A until S22B. In this paper, we report on details of on-sky performance of the instrument evaluated during the engineering observations for a total of 7.5 nights.

"A joint project has been proposed by the Chinese and Spanish astronomy communities, to develop a high-resolution, ultra- stable spectrograph for the Gran Telescopio Canarias (GTC) at La Palma. Being expected to conduct precise radial velocity (PRV) measurement with extreme precision of up to 10 cm s⁻¹, the instrument would promote the very high, present interest in the astronomical community to detect and characterize exoplanets. The project successfully passed the conceptual design review (CoDR) in 2019. The instrument is composed of a near-UV band spectrograph (UVS) and a visible band spectrograph (VIS). They provide a spectral resolving power of R ≥100,000 in the visible band (420 nm – 780 nm), and R≥25,000 in the UV band (310 nm – 420 nm). The VIS subsystem will be enclosed in an ultra-stable environment in the Coudé room for the stellar precise radial velocity (PRV) measurements. T he UVS subsystem will be located near the Nasmyth focus to improve the total throughput at the wavelength shorter than 400 nm, to ensure various additional science cases ranging from stellar evolution to the measurement of fundamental constants. This paper gives an overview of the project background, science cases, and technical considerations during the conceptual design phase."

We present the preliminary design of Cerberus, a new scientific instrument for the alt-az, 80cm OARPAF telescope in the Ligurian mountains above Genoa, Italy. Cerberus will provide three focal stations at the Nasmyth focus, allowing: imaging and photometry with standard Johnson-Cousins UBV RI+Hα+Free filters, an on-axis guiding camera, and a tip-tilt lens for image stabilization up to 10Hz; long slit spectroscopy at R 5900 thanks to a LHIRES III spectrograph provided with a 1200l/mm grism; echelle spectroscopy at R 9300 using a FLECHAS spectrograph with optical fiber.

We report the development of MuSCAT3, a four channel simultaneous imager installed on the 2m Faulkes Telescope North at Haleakala Observatory on Maui, Hawai’i. MuSCAT3 has a capability of 4-color simultaneous imaging in g (400–550 nm), r (550–700 nm), i (700–820 nm), and z_s (820–920 nm) bands with four independent 2048×2048 pixel CCDs, each having a field of view of 9.1×9.1 arcmin² with a pixel scale of 0.27 arcsec per pixel. The development of MuSCAT3 started from September 2019, and MuSCAT3 achieved its first light on September 28th, 2020. The Las Cumbres Observatory started science operations of MuSCAT3 since November 4th, 2020, although a part of its capabilities are still limited.

We present our progress on the UV-VIS arm of Son Of X-Shooter (SOXS), a new spectrograph for the NTT. Our design splits the spectral band into four sub-bands that are imaged onto a single detector. Each band uses an optimized high efficiency grating that operates in 1st order (m=1). In our previous paper we presented the concept and preliminary design. SOXS passed a Final Design Review in July 2018 and is well into the construction phase. Here we present the final design, performances of key manufactured elements, and the progress in the assembly. Based on the as-built elements, the expected throughput of the visual arm will be < 55%. This paper is accompanied by a series of contributions describing the progress made on the SOXS instrument.

BlueMUSE (Blue Multi Unit Spectroscopic Explorer) is a blue-optimised, medium spectral resolution, panoramic integral field spectrograph proposed for the Very Large Telescope (VLT) and based on the MUSE concept. BlueMUSE will open up a new range of galactic and extragalactic science cases allowed by its specific capabilities in the 350 - 580 nm range: an optimised end-to-end transmission down to 350 nm, a larger FoV (up to 1.4 x 1.4 arcmin²) sampled at 0.3 arcsec, and a higher spectral resolution (λ/Δλ ~ 3500) compared to MUSE. To our knowledge, achieving such capabilities with a comparable mechanical footprint and an identical detector format (4k x 4k, 15 µm CCD) would not be possible with a conventional spectrograph design. In this paper, we present the optomechanical architecture and design of BlueMUSE at pre-phase A level, with a particular attention to some original aspects such as the use of curved detectors.

We present here the development status of the NIR spectrograph of the Son Of X-Shooter (SOXS) instrument, for the ESO/NTT telescope at La Silla (Chile). SOXS is a R~4,500 mean resolution spectrograph, with a simultaneously coverage from about 0.35 to 2.00 μm. It will be mounted at the Nasmyth focus of the NTT. The two UV-VIS-NIR wavelength ranges will be covered by two separated arms. The NIR spectrograph is a fully cryogenic echelle-dispersed spectrograph, working in the range 0.80-2.00 μm, equipped with a Hawaii H2RG IR array from Teledyne. The whole spectrograph will be cooled down to about 150 K (but the array at 40 K), to lower the thermal background, and equipped with a thermal filter to block any thermal radiation above 2.0 μm. In this work, we will show the advanced phase of integration of the NIR spectrograph.

IMSP is the versatile first-light instrument under construction for the 4m telescope in China. The special feature of IMSP is the multimode operation modes and high-efficiency. Direct imaging mode is designed to work in a synchronous multi-color bands covering from 360 to 1700 nm using two dichroic mirrors with a 3’x3’ field of view (FOV). Long-slit spectrograph mode supports two spectral resolutions operation modes (R=1000 and 5000) via different combination of Volume Phase Holographic Prisms to cover the whole spectrum in visible. High resolution spectrograph mode (R=30000-60000) with wavelength range from 380 to 800 nm is reserved using fiber link system connected from Nasmyth foci to the enviroment controled room. The IMSP is planned to strart commssion at the end of 2021. In this paper, the lastest status of IMSP development will be given, including the final optical design and the integration of each sub-system.

The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a four-channel adaptive-optics-assisted integralfield spectrograph being designed for the Gemini 8-meter telescopes. Deployed behind the Gemini-North Adaptive Optics (GNAO) system, it will provide spatially-resolved spectra over the 0.9-2.4 um wavelength range for four fields simultaneously. Its multi-object adaptive optics will provide additional correction of the target fields, beyond that achieved by the GNAO system, enabling integral-field spectroscopy with near-diffraction-limited resolution and unprecedented sensitivity. A parallel imaging channel will view the field of regard and provide a simultaneous imaging capability. The primary science objectives include mapping chemical abundances, star formation and kinematics in high-redshift galaxies, and studies of stellar populations, star formation and supermassive black holes in nearby galaxies. In order to support the science programs, GIRMOS requires a system that enables photometric, spectroscopic and astrometric calibration. The GIRMOS Calibration System (CAL) serves this purpose, uniformly illuminating the spectroscopic and imaging channels with both continuous and narrow-line light for flat-field and wavelength calibration. In order to replicate the light path through the instrument as closely as possible, the CAL optical system matches both the pupil position and the focal ratio of the beam delivered to the instrument by GNAO. CAL also includes a metrology system, employing focal-plane masks, to permit precise calibration of the positions of the pick-off arms of the object selection system, and to map optical distortion and instrument flexure. This paper summarizes the key requirements of the CAL system, presents its conceptual design and discusses its expected performance.

The Fully Automatic Spectrograph for Transient (FAST) is an instrument under development which is going to be installed in the PROMPT-7 a 100% robotic telescope with an excellent guiding accuracy. FAST is a low resolution spectrograph (R = 60 and 600 at 6500Å) covering the 3800Å to 9200Å wavelength range that includes an imaging mode. The instrument is expected to help the astronomical community to obtain the first spectrum of the transient, without human intervention, in a few minutes after its discovery. In this work we present a description of the instrument: the spectrographs principal parameters the instrument’s design. It also discussed the current state of the project and challenges that we have encounter.

We have developed an integral field unit (IFU) for the existing optical imaging spectrograph, Faint Object Camera And Spectrograph (FOCAS), on the Subaru telescope. FOCAS IFU finally saw a first light on March 2nd, 2018, and started the common use from 2019. In order to observe faint targets like distant galaxies, our IFU has a coarse sampling comparable to the best seeing size and high throughput. The field of view is 13.4 10.0 arcsec² which is divided into 23 slices with the width of 0.435 arcsec. Our IFU has a slit separated by about 5.2 arcmin from an object field in order to simultaneously obtain a sky spectrum. We confirmed that the image quality is good enough for the 0.435-arcsec slice width and the best seeing size of 0.4 arcsec. Mean and median throughput of the IFU are respectively 85.0% and 87.3%. However some fields show lower throughput due to misalignment of the IFU optics and the worst throughput is 61.9% at one field corner. Flat fielding error is almost within ±3%, but worse errors are found at the low-throughput region. The worst error is 9% at the lowest throughput region.

We describe and present initial testing of TCal, a mobile spectrophotometric calibration system that will be used to characterize the throughput as a function of wavelength for imaging systems at observatories around the world. TCal measurements will enhance the science return from follow-up observations of imaging surveys such as LSST (Large Synoptic Survey Telescope) and DES (Dark Energy Survey) by placing all tested imaging systems on a common photometric baseline. TCal uses a ~ 1 nm bandpass tunable light source to measure the instrumental response function of imaging systems from 300 nm to 1100 nm, including the telescope, optics, filters, windows, and detector. The system is comprised of a monochromator-based light source illuminating a dome flat field screen monitored by a calibrated CCD, which allows determination of the telescope throughput as a function of wavelength. This calibration will be performed at 1-8m telescopes that expect to devote time towards survey follow-up. Performing the calibration on these telescopes will reduce systematic errors due to small differences in bandpass, making follow-up efforts more precise and accurate.

SOXS (Son Of X-Shooter) will be the new medium resolution (R∼4500 for 100 slit), high-efficiency, wide band spectrograph for the ESO NTT at La Silla, optimized for classification and follow-up of transient events. SOXS will simultaneously cover UV-optical and NIR bands (0.35-2.00 micron) using two different arms and a pre-slit Common Path feeding system. The instrument will be also equipped by a Calibration Unit and an Acquisition Camera (AC) System. In this paper we present the final opto-mechanical design for the AC System and we describe its development status. The project is currently in manufacturing and integration phases.

Differential atmospheric dispersion, due to the wavelength-dependent index of refraction of the atmosphere, will affect ground based observations. In order to correct this effect, the usage of an Atmospheric Dispersion Corrector (ADC) is fundamental. Insufficient, or wrong correction of the atmospheric dispersion, will produce a spectrally elongated shape instead of a circular white one for the observed target. The commissioning tests of ADCs with on-sky observations are not an easy task. In fact, the residual dispersion is expected to be of a few tens of milliarcsec, where the object for a seeing limited telescope is almost 1 arcsec. A procedure was developed, based on ellipse fitting of several cuts from the guiding camera images. The characterization of the data allows the validation of the ADCs alignment by determining the dispersion direction and by minimizing the ellipticity. The procedure was tested on ESPRESSO using the guiding camera images, and was able to correct a small error of a few degrees in the ADC prism alignment that was not possible to infer by other means.

The Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU) is developed as the first-generation mid-infrared instrument for the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU performs medium-band imaging and low-resolution spectroscopy in 2-38 microns and enables highest-spatial-resolution observations in the long-wavelength mid-infrared beyond 25 microns. In addition, MIMIZUKU has a unique opto-mechanical device called ‘Field Stacker’, which enables us to observe a distant (<25 arcminutes) pair of target and reference objects simultaneously and improves accuracy of atmospheric calibration. This function is expected to improve photometric accuracy and quality of spectroscopic data even in the long-wavelength mid-infrared regions, where the atmospheric absorption is severe. In 2018, engineering observations of MIMIZUKU were carried out at the Subaru telescope, and its first-light was successfully achieved. In the engineering observations, the imaging and spectroscopic functions in the mid-infrared wavelengths (7.6-25 microns) were confirmed to be working almost as expected, although the sensitivity is still worse than the background-limited performance by a factor of a few due to high readout noise. The Field Stacker was also confirmed to be working as expected. It is confirmed that the photometric instability can be reduced to a few percent by using Field Stacker even when the atmospheric transmittance varies by 10% in time. It is also confirmed that spectroscopic observations can be performed not only in 10-micron band but also in 20-micron band, where the spectroscopic observations are difficult even at the Mauna Kea site. We report the results of these on-sky performance evaluations.

WIRC+Pol is a J and H-band spectropolarimetric mode for the prime-focus WIRC camera at the Palomar 200-inch Hale telescope. The mode has been enabled with the installation of a split-pupil polarization grating in Feburary 2017. The polarization grating was designed for the simultaneous measurement of Stokes Q and U without the use of a modulator at a seeing-limited spectral resolving power of 100. WIRC+Pol can operate in both a slitless mode and with a 3” slit. To overcome time-dependent instrumental polarization effects that limited the calibration of instrumental polarization to a 1% level, in February 2019 we installed a linear polarizer and half-wave plate modulator in front of the instrument, both of which are rotatable. With this design the primary mirror is the only optic in front of the modulator. The new upgrade has allowed us to calibrate the instrumental polarization to less than 0.1%. Here we present a detailed description of the upgrade and report on WIRC+Pol’s post-upgrade on-sky performance based on observations of unpolarized and polarized standard stars. We have used the observations of polarized standard stars to develop a wavelength-dependent polarimetric instrument model that we characterize as a function of time and focal-plane location.