We are presenting in this work, the final design of the Multi-Object Adaptive Optics system for the Gemini InfraRed Multi Object Spectrograph (GIRMOS). This report outlines key modifications made during the critical design phase as we progress towards the manufacturing assembly integration and testing stage. Our adjustments include in particular, the wavefront sensor subassembly through the selection of a new camera and by optimizing the number of sub-apertures and pixels. Additionally, recent advancements in the Gemini North Adaptive Optics (GNAO) design prompt a reassessment of Ground Layer Adaptive Optics (GLAO) and tomographic performance, thus influencing both multi-Objects Adaptive Optics (MOAO) and the GIRMOS imager. The final optical and mechanical design of the MOAO subsystem as well as the revisited performance is discussed. Since the beginning of the project, we have identified some risks associated to the MOAO system and developed mitigation strategies and activities. We report the progress made towards the mitigation of identified risks such as open-loop calibration and control, go-to errors, quasi-static errors, etc. A primary objective driving the development of GIRMOS is the survey of a substantial sample of high-redshift galaxies. Using AO observations of z~2 galaxies, as seen with SINFONI at the Very Large Telescope, and employing image processing techniques with various GIRMOS simulated point spread functions (PSFs), we methodically explore the GIRMOS ability to detect and characterize star-forming clumps within high-redshift galaxies. This analysis provides valuable insights into optimal target selection based on their positioning in the field of view, on the observing conditions (such as seeing, zenith angle, etc.), and the intended scientific objectives.
The Gemini Infrared Multi-Object Spectrograph (GIRMOS) is a new facility instrument being designed in close partnership with the upcoming facility adaptive optics (AO) system at Gemini-North observatory called GNAO. GIRMOS will carry out high angular resolution (0.83 – 2.4 µm) imaging and multi-object integral field (0.95 – 2.35 µm) spectroscopy within GNAO’s two arcminute field-of-regard. GIRMOS consists of an imager and four identical deployable integral field spectrographs with a multi-object AO system that provides an additional image quality improvement for each spectrograph over GNAO across the full field. We present the final design overview of GIRMOS, which will be entering the construction phase in 2024 with an expected delivery in 2027. GIRMOS is a pathfinder for future extremely large telescope instrumentation that requires high angular resolution, highly multiplexed spectroscopy.
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 mechanical design and optical alignment of the lens barrels used for the two cameras in the instrument. A divide and conquer approach was used. Camera lenses were aligned to their respective individual cells for the tilt and axial spacing, and then bonded to flexures for stability. Centering of the lens to each other was done as the individual cells were stacked into barrels. Alignment in tilt and axial position was performed on Laser Alignment and Assembly Station (LAS) manufactured by Opto-Alignment Technology, Inc. Design of the individual optical cells provides low-stress restraint and at the same time ensures high rigidity and long-term mechanical stability of the mount.
The Gemini High-Resolution Optical SpecTrograph (GHOST) instrument is the next generation high resolution spectrograph for the Gemini telescope. The GHOST instrument was developed for the Gemini telescope as a collaboration between Australian Astronomical Optics (AAO) at Macquarie University, 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. The bench spectrograph was integrated at Gemini South from April to June 2022. This paper presents the final integration and alignment of the spectrograph at Gemini South and the measured spectrograph performance at the telescope.
The Gemini High-Resolution Optical SpecTrograph (GHOST) is the next in line instrument being integrated for the Gemini south telescope, in a collaboration between the Australian Astronomical Optics (AAO) at Macquarie University, Herzberg Astronomy and Astrophysics (HAA) at the National Research Council Canada, and the Australian National University (ANU). This paper will discuss shipping considerations and data taken by the NRC-Herzberg and Gemini team to preserve and protect the instrument during a two year hiatus brought on by the COVID-19 pandemic.
High-contrast imaging instruments have advanced techniques to improve contrast, but they remain limited by uncorrected stellar speckles, often lacking a “second stage” correction to complement the Adaptive Optics (AO) correction. We are implementing a new second stage speckle-correction solution for the Gemini Planet Imager (GPI), replacing the instrument calibration unit (CAL) with the Fast Atmospheric Self coherent camera Technique (FAST), a new version of the self-coherent camera (SCC) concept. Our proposed upgrade (CAL2.0) will use a common-path interferometer design to enable speckle correction, through post-processing and/or by a feedback loop to the AO deformable mirror. FAST utilizes a new type of coronagraphic mask that will enable, for the first time, speckle correction down to millisecond timescales. The system's main goal is to improve the contrast by up to 100x in a halfdark hole to enable a new regime of science discoveries. Our team has been developing this new technology at the NRC's Extreme Wavefront control for Exoplanet and Adaptive optics Research Topics (NEW EARTH) laboratory over the past several years. The GPI CAL2.0 update is funded (November 2020), and the system’s first light is expected late 2023.
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.
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 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.
The Gemini High-Resolution Optical SpecTrograph (GHOST) is the newest instrument chosen for the Gemini South telescope. It is being developed by a collaboration between the Australian Astronomical Observatory (AAO), the NRC - Herzberg in Canada and the Australian National University (ANU). Using recent technological advances and several novel concepts it will deliver spectroscopy with R>50,000 for up to 2 objects simultaneously or R>75,000 for a single object. GHOST uses a fiber-image-slicer to allow use of a much smaller spectrograph than that nominally required by the resolution-slit–width product. With its fiber feed, we expect GHOST to have a sensitivity in the wavelength range between 363-950 nm that equals or exceeds that of similar directly-fed instruments on world-class facilities. GHOST has entered the build phase. We report the status of the instrument and describe the technical advances and the novel aspects, such as the lenslet-based slit reformatting. Finally, we describe the unique scientific role this instrument will have in an international context, from exoplanets through stellar elemental abundances to the distant Universe. Keywords: Gemini, spectrograph, spectroscopy, ́echelle, high resolution, radial velocity, fiber image slicer, integral field unit.
The Gemini Planet Imager (GPI) is a facility extreme-AO high-contrast instrument – optimized solely for study of faint companions – on the Gemini telescope. It combines a high-order MEMS AO system (1493 active actuators), an apodized pupil Lyot coronagraph, a high-accuracy IR post-coronagraph wavefront sensor, and a near-infrared integral field spectrograph. GPI incorporates several other novel features such as ultra-high quality optics, a spatially-filtered wavefront sensor, and new calibration techniques. GPI had first light in November 2013. This paper presnets results of first-light and performance verification and optimization and shows early science results including extrasolar planet spectra and polarimetric detection of the HR4696A disk. GPI is now achieving contrasts approaching 10-6 at 0.5” in 30 minute exposures.
The Gemini Remote Access to CFHT ESPaDONS Spectrograph has achieved first light of its experimental phase in May
2014. It successfully collected light from the Gemini North telescope and sent it through two 270 m optical fibers to the
the ESPaDOnS spectrograph at CFHT to deliver high-resolution spectroscopy across the optical region. The fibers gave
an average focal ratio degradation of 14% on sky, and a maximum transmittance of 85% at 800nm. GRACES achieved
delivering spectra with a resolution power of R = 40,000 and R = 66,000 between 400 and 1,000 nm. It has a ~8%
throughput and is sensitive to target fainter than 21st mag in 1 hour. The average acquisition time of a target is around 10 min. This project is a great example of a productive collaboration between two observatories on Maunakea that was
successful due to the reciprocal involvement of the Gemini, CFHT, and NRC Herzberg teams, and all the staff involved
closely or indirectly.
The Gemini High-Resolution Optical SpecTrograph (GHOST) is the newest instrument being developed for the Gemini telescopes, in a collaboration between the Australian Astronomical Observatory (AAO), the NRC - Herzberg in Canada and the Australian National University (ANU). We describe the process of design optimisation that utilizes the unique strengths of the new partner, NRC - Herzberg, the design and need for the slit viewing camera system, and we describe a simplification for the lenslet-based slit reformatting. Finally, we out- line the updated project plan, and describe the unique scientific role this instrument will have in an international context, from exoplanets through to the distant Universe.
A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility
for the entire 340 - 950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile
instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these
relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R =
90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets
over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process
that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this
paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of
Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct
a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the
science case development and requirements flow-down process that leads to the configuration of the HIA instrument and
describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the
conceptual design study.
The Gemini Planet Imager is a next-generation instrument for the direct detection and characterization of young warm exoplanets, designed to be an order of magnitude more sensitive than existing facilities. It combines a 1700-actuator adaptive optics system, an apodized-pupil Lyot coronagraph, a precision interferometric infrared wavefront sensor, and a integral field spectrograph. All hardware and software subsystems are now complete and undergoing integration and test at UC Santa Cruz. We will present test results on each subsystem and the results of end-to-end testing. In laboratory testing, GPI has achieved a raw contrast (without post-processing) of 10-6 5σ at 0.4”, and with multiwavelength speckle suppression, 2x10-7 at the same separation.
The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory
to participate in a competitive conceptual design study for a new Gemini High-Resolution Optical Spectrograph
(GHOS). Concurrently this same group is working in partnership with both the Gemini and CFH Telescopes to
design the Gemini Remote Access to CFHT ESPaDOnS Spectrograph, (GRACES). Both these instruments will use
a fiber feed allowing light received by the Gemini telescope to be processed via remotely positioned instruments.
This paper will explore the similarities and differences in requirements, inherent challenges, concepts, design
solutions and areas of concept sharing.
The Gemini Remote Access CFHT ESPaDOnS Spectrograph (GRACES) is an innovative instrumentation experiment
that will demonstrate if ESPaDOnS, a bench-mounted high-resolution optical spectrograph at CFHT, can be fed by a
270-m long fiber from the Gemini-North telescope with low enough losses to remain competitive with conventional
spectrographs on other 8 to 10-m telescopes. Detailed simulations have shown that GRACES should be more sensitive
than the HIRES spectrograph at Keck Observatory at wavelengths longer than about 600-700 nm. This result is possible
by using FPB-type of optical fibers made by Polymicro Technologies and by keeping the critical focal ratio degradation
(FRD) losses to less than 10%. Laboratory tests on these FPB optical fibers are underway and show that for 36-m lengths
that the FRD losses are as low as 0.8% with a repeatability of 1%. Tests are currently underway on 280-m lengths.
The Herzberg Institute of Astrophysics was recently selected by the Gemini Observatory as one of the three competing
organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS).
This paper outlines the main features of the mechanical design, including the Cassegrain-mounted science input unit, the
bench-mounted spectrograph and the fiber relay system. Topics include the design challenges associated with multiobject
fiber relays in the science unit, environmental stability of the spectrograph bench and routing and handling of
fibers in the Gemini dome environment.
K. Arnold, P. Ade, A. E. Anthony, F. Aubin, D. Boettger, J. Borrill, C. Cantalupo, M. A. Dobbs, J. Errard, D. Flanigan, A. Ghribi, N. Halverson, M. Hazumi, W. Holzapfel, J. Howard, P. Hyland, A. Jaffe, B. Keating, T. Kisner, Z. Kermish, A. Lee, E. Linder, M. Lungu, T. Matsumura, N. Miller, X. Meng, M. Myers, H. Nishino, R. O'Brient, D. O'Dea, H. Paar, C. Reichardt, I. Schanning, A. Shimizu, C. Shimmin, M. Shimon, H. Spieler, B. Steinbach, R. Stompor, A. Suzuki, T. Tomaru, H. T. Tran, C. Tucker, E. Quealy, P. Richards, O. Zahn
POLARBEAR is a Cosmic Microwave Background (CMB) polarization experiment that will search for evidence
of inflationary gravitational waves and gravitational lensing in the polarization of the CMB. This proceeding
presents an overview of the design of the instrument and the architecture of the focal plane, and shows some of
the recent tests of detector performance and early data from the ongoing engineering run.
We have performed some initial characterization of back-illuminated deep-depletion CCDs from Hamamatsu Photonics.
Three of these 2048×4096, three-side buttable devices will replace the current CCDs in the Gemini Multi-Object
Spectrograph to improve the performance of the instrument in the red and near-infrared wavelengths. We describe our
testing campaign and report on the results.
The instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory to
develop and implement a new focal plane assembly with an array of three Hamamatsu CCDs for the Gemini Multi-
Object Spectrographs[1,2]. This paper describes the overall design of the new focal plane system with respect to the
existing interface and requirements and outlines the test methodology to validate the new system against its performance
requirements. The characterization and performance optimization processes of the Hamamatus CCDs are also described.
WFOS (Wide Field Optical Spectrograph) will provide near-UV, visible and near-IR multi-object spectroscopy and imaging capabilities for the TMT (Thirty Meter Telescope). The instrument concept is a multi-barrel approach, with four separate fields on the telescope focal plane providing a total of 92.4 square arcminutes of coverage. The core wavelength coverage is 340nm to 1000nm with an optional near-IR extension to 1.6 microns. Each barrel feeds two cameras allowing simultaneous spectral coverage in the blue and red. Spectral resolutions range from R150 to R7500 for a 0.75" slit using standard ruled transmission gratings and VPH technology. A GLAO (Ground Layer Adaptive Optics) system utilizing the TMT adaptive secondary mirror is included in the instrument concept. This paper describes the scientific goals for WFOS and the overall instrument mechanical, optical and system design.
The Six Degree-of-Freedom (6DOF) positioner was developed to position the four off-axis conic mirrors in Altair (Gemini** North's facility adaptive optics system). This positioner takes a unique approach to 6DOF positioning by combining two 3DOF parallel mechanisms in series to create a hybrid mechanism. The mechanism design provides a number of benefits including small size, simple adjustment, position locking, relatively simple kinematics and repeatable removal and replacement of optical components.
The 6DOF positioner is capable of positioning optics at the micron level in translation and at the arcsecond level in rotation. It also maintains the position of the optics to a few microns with changing gravity vector. The position of an attached optical component can be adjusted using a computer program to provide precision adjustment about an arbitrary coordinate system. However, the arrangement of the adjustments are such that any desired motion can be made with a single actuator or with a sensible combination of actuators. This is unlike other 6DOF positioning solutions like a Stewart Platform in which all 6DOF are completely coupled making it impossible to move the platform in any desired direction without moving all six actuators.
This paper will present the design of the positioner, a kinematic analysis of the mechanism and a discussion about the effectiveness of the positioner in the optical alignment of Altair.
A 350GHz 4 × 4 element heterodyne focal plane array using SIS detectors is presently being constructed for the JCMT. The construction is being carried out by a collaborative group led by the MRAO, part of the Astrophysics Group, Cavendish Laboratory, in conjunction with the UK-Astronomy Technology Centre (UK-ATC), The Herzberg Institute of Astrophysics (HIA) and the Joint Astronomy Center (JAC). The Delft Institute of Microelectronics & Sub-micron Technology (DIMES) is fabricating junctions for the SIS mixers that have been designed at MRAO.
Working in conjunction with the 'ACSIS' correlator & imaging system, HARP-B will provide 3-dimensional imaging capability with high sensitivity at 325 to 375GHz. This will be the first sub-mm spectral imaging system on JCMT - complementing the continuum imaging capability of SCUBA - and affording significantly improved productivity in terms of speed of mapping. The core specification for the array is that the combination of the receiver noise temperature and beam efficiency, weighted optimally across the array will be <330K SSB for the central 20GHz of the tuning range.
In technological terms, HARP-B synthesizes a number of interesting and innovative features across all elements of the design. This paper presents both a technical and organizational overview of the HARP-B project and gives a description of all of the key design features of the instrument. 'First light' on the instrument is currently anticipated in spring 2004.
The Convex Camera Structure (CCS) is a welded Invar structure that supports of the final two optical elements in the Altair science path. The CCS assembly holds the large camera mirror, a 295 mm diameter off-axis conic, in close relation with the smaller convex mirror, a 146 mm diameter off-axis conic. The image quality requirement imposed stringent spatial tolerance between the two mirrors: +/- 45 micrometers in axial separation, +/- 70 micrometers in decenter and +/- 30 arcsecond in allowable tilt. These tolerances include contributions from initial alignment error, geometrical and dimensional changes due to gravity and temperature. This paper gives an overview of the CCS and its associated components. Flexures are integral part of the CCS assembly, they are utilized to connect the CCS to the aluminum main optical bench, the mirror to the six degree- of-freedom mount, and the 6DOF mount to the CCS end plate. The design considerations and engineering analyses of the CCS assembly are outlined.
Mechanically Actuated Reconfigurable Slits (MARS) provide a remote means of creating and reconfiguring multi-object spectrograph slits. The MARS design provides 99 individually positionable variable-width slits over a 180 mm square telescope focal plane. It offers fast, remote configurable, suitable for optical and IR ground and space based multi- object spectrographs. The slit apertures are arranged in three columns, to optimize the placement of the spectra on the detector. Two distinct MARS designs are presented, mechanically actuated strips and mechanically actuated rolls. The methods configure the slits by translating thin strips of material across the telescope focal pane. Slits are formed either by an aperture cut in the strip or by bringing two separate strips together head-to-head.
Altair is the facility adaptive optics system for the Gemini-North 8-meter Telescope. This paper gives an overview of the key mechanical systems and feature of Altair including the optical bench assembly mechanics and opto- mechanics, the instrument structure, and the electronics enclosure.
The Gemini Adaptive Optics System, (Altair), under construction at the National Research Council of Canada's Herzberg Institute of Astrophysics is unique among AO systems. Altair is designed with its deformable mirror (DM) conjugate to high altitude. We summarize construction progress. We then describe Altair in more detail. Both the Wavefront sensor foreoptics and control system are unconventional, because the guide star footprint on an altitude-conjugated DM moves as the guide star position varies. During a typical nodding sequence, where the telescope moves 10 arcseconds between exposures, this footprint moves by half an actuator and/or WFS lenslet. The advantages of altitude conjugation include increased isoplanatic patch size, which improves sky coverage, and improved uniformity of the corrected field. Altitude conjugation also reduces focal anisoplanatism with laser beacons. Although the initial installation of Altair will use natural guide stars, it will be fully ready to use a laser guide star (LGS). The infrastructure of Gemini observatory provides a variety of wavefront sensors and nested control loops that together permit some unique design concepts for Altair.
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