We present H alpha-region integral-field spectroscopy for 137 low-inclination, intermediate to late-type galaxies. Spectroscopic data, obtained with SparsePak and the Bench Spectrograph on the WIYN 3.5 m telescope, span 6475-6880 angstrom with an instrumental resolution of 13 km s(-1) (sigma). The spectral range includes H alpha and [N II]lambda lambda 6548, 6584 for every source, and in most cases includes [S II]lambda lambda 6717, 6731. We present and publicly release 18,288 calibrated spectra and visually inspected Gaussian line fits to the H alpha emission. Most measurements yield a signal-to-noise ratio above 5 in integrated H alpha line flux, adequate to derive reliable line centroids and widths. Second kinematic components are required to adequately describe the emission-line profile in 15% of reliable data. The H alpha velocity dispersion distribution peaks at 18 km s(-1), modestly increasing with H alpha surface brightness, reaching 20 km s(-1) at Sigma(H alpha) = 10(40) erg s(-1) kpc(-2). Lower-flux secondary components, when present, have widths of similar to 50 km s(-1). These results agree well with previous echelle measurements of nearby galaxies. Velocity-field analysis yields kinematic inclinations, with a sample mean of 26 degrees. Large kinematic asymmetries systematically affect kinematic inclination estimates in a small fraction of our sample. When deviations from circular motion are below 10% of the projected velocity, kinematic inclinations are consistent, within errors, to estimates from inverting the Tully-Fisher relation. This confirms previous disk-submaximality estimates for galaxies with regular kinematics based on inclinations derived from inverting the Tully-Fisher relation.
Liger is a next-generation near-infrared (0.81 - 2.45 mu m) integral field spectrograph (IFS) and imaging camera for the W. M. Keck Observatory (WMKO) adaptive optics (AO) system. The instrument concept originated by coupling designs from WMKO AO instruments and the future Thirty Meter Telescope IRIS spectrograph. Liger is designed for the Keck I telescope to operate behind the upcoming Keck All-sky Precision Adaptive optics (KAPA) system. The imaging camera sequentially feeds an IFS that makes use of slicer assembly for the coarsest sampling (75 mas and 150 mas per spaxel) and lenslet array (14 mas and 31 mas per spaxel) for diffraction-limited sampling. The imaging camera makes use of off-axis parabolas and a Hawaii-2RG detector to achieve a 14 mas/pixel plate scale and 20.5 '' x20.5 '' field of view. The IFS offers a range of spectral resolving power of R=4,000 10,000 and yields large fields of view for an AO-fed IFS. Liger will enable new science by providing enhanced capabilities, including higher spectral resolving power, access to shorter wavelengths, and larger fields of view than any current or planned ground- or space-based IFS system. Liger will be able to unlock previously inaccessible science across a wide range of the cosmos, such as dark matter substructure, supermassive black holes, the Galactic Center, exoplanet atmospheres, and the time-variable Solar System. We present the overall design of the Liger subsystems and review unique science drivers.
The Infrared Imaging Spectrograph (IRIS) is a diffraction-limited instrument designed for the Thirty Meter Telescope (TMT) through an international collaboration. IRIS works in tandem with the Narrow-Field InfraRed Adaptive Optics System (NFIRAOS) and covers a near-infrared spectral range of 0.84 to 2.4 microns. IRIS and NFIRAOS will be the instruments used to demonstrate first light at TMT. IRIS incorporates a wide-field Imager with a fixed plate scale of 4 milliarcseconds (mas), and an Integral Field Spectrograph (IFS) offering four plate scales that range from 4 mas to 50 mas. In 2021, the major subsystems of IRIS went through final design reviews. This paper provides an update on IRIS design and outlines the plan for its fabrication, integration, and delivery to TMT for first light.
We present details of the recent trade study on design changes to the Wide Field Optical Spectrometer (WFOS) for the Thirty Meter Telescope (TMT)[1]. WFOS is planned as a first light instrument and will provide highly efficient imaging and multi-slit spectroscopy over the wavelength range 0.31 to 1 mu m across a field of view of 8.3 by 3 arcminutes. The existing baseline prior to the trade study used a laser cut metal slit mask at the focal plane to enable observation of similar to 50 to 80 objects simultaneously. The masks would be cut in advance of observing and installed in a cassette, allowing a mechanism to select the mask and move it into place at the focal plane. Each multi-object observation requires a dedicated mask, with a more general single long slit mask remaining in the cassette permanently. The configurable slit unit (CSU) is an alternative approach, and a design that has previously been used in MOSFIRE and FORS. A CSU uses multiple knife edges mounted on computer-controlled bars to create and position slits at the focal plane. In the case of WFOS the CSU will be capable of creating 96 separate slits with the ability to reconfigure them on the fly to adapt to seeing conditions or to respond to targets of opportunity. We detail here the decision criteria, design, and science case analysis used by the WFOS team to decide to change the baseline design of WFOS to incorporate a CSU.
ABSTRACT We present the deepest J −Ks near-infrared photometry of the globular cluster M5 (NGC 5904) from observations taken with the Gemini South Adaptive Optics Imager in tandem with the Gemini Multi-conjugate adaptive optics System (GeMS) on the 8.1-m Gemini South telescope. Point spread function (PSF) photometry was carried out using a spatially variable PSF, zero-point calibrations based on correlations to a standard photometric catalogue, colour corrections, and crowding corrections. The latter corrections provided a new challenge given the field variations of the adaptive optics corrections in the central crowded regions of this cluster. The final photometric precision in our J− Ks colour–magnitude diagram exposes a dispersion among the lower main-sequence stars of M5 for the first time. This dispersion occurs below a main-sequence knee due to variations in the helium and CNO (carbon, nitrogen, and oxygen) abundances from multiple stellar populations, consistent with results from the bright evolved stars in this cluster from ultraviolet to near-infrared Hubble Space Telescope photometry and ground-based spectroscopy. This paper completes our original GeMS quality analysis programme, providing insights into adaptive optics analyses in crowded fields.
NFIRAOS (Narrow-Field InfraRed Adaptive Optics System) will be the first-light multi-conjugate adaptive optics system for the Thirty Meter Telescope (TMT). The system will be built, tested, and integrated with the first instrument, IRIS (InfraRed Imaging Spectrograph), at Herzberg Astronomy and Astrophysics (HAA) in Victoria BC. NFIRAOS is a complex instrument that will require careful integration planning to meet cost, schedule and performance deliverables. HAA has purpose-built a new facility for the integration of NFIRAOS. We present the key features of this building, and their roles during the assembly, integration, and test phase (AIV). NFIRAOS and IRIS will be fully operational in Victoria, including providing calibration sources, and able to close the adaptive optics (AO) loops with the IRIS On-Instrument Wavefront sensors. NFIRAOS will then be disassembled and shipped to TMT for final construction and commissioning, which requires navigating some logistical challenges.
At first light, the Thirty Meter Telescope (TMT) near-infrared (NIR) instruments will be fed by a multiconjugate adaptive optics instrument known as the Narrow Field Infrared Adaptive Optics System (NFIRAOS). NFIRAOS will use six laser guide stars to sense atmospheric turbulence in a volume corresponding to a field of view of 2′, but natural guide stars (NGSs) will be required to sense tip/tilt and focus. To achieve high sky coverage (50% at the north Galactic pole), the NFIRAOS client instruments use NIR on-instrument wave front sensors that take advantage of the sharpening of the stars by NFIRAOS. A catalog of guide stars with NIR magnitudes as faint as 22 mag in the J band (Vega system), covering the TMT-observable sky, will be a critical resource for the efficient operation of NFIRAOS, and no such catalog currently exists. Hence, it is essential to develop such a catalog by computing the expected NIR magnitudes of stellar sources identified in deep optical sky surveys using their optical magnitudes. This paper discusses the generation of a partial NIR Guide Star Catalog (IRGSC), similar to the final IRGSC for TMT operations. The partial catalog is generated by applying stellar atmospheric models to the optical data of stellar sources from the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) optical data and then computing their expected NIR magnitudes. We validated the computed NIR magnitudes of the sources in some fields by using the available NIR data for those fields. We identified the remaining challenges of this approach. We outlined the path for producing the final IRGSC using the Pan-STARRS data. We have named the Python code to generate the IRGSC as irgsctool , which generates a list of NGS for a field using optical data from the Pan-STARRS 3pi survey and also a list of NGSs having observed NIR data from the UKIRT Infrared Deep Sky Survey if they are available. irgsctool is available in the public domain on this GitHub public repository ( https://github.com/sshah1502/irgsc ), while the generated and validated IRGSC for the 20 test fields and additional Pan-STARRS Medium Deep Survey fields can be found on Zenodo.
REVOLT (Research, Experiment and Validation of Adaptive Optics with a Legacy Telescope) is an adaptive optics (AO) system on the 1.2-m telescope at the Herzberg Astronomy and Astrophysics Research Centre which is intended to demonstrate various AO developments, technologies, and algorithms. This AO system is a platform to test the Herzberg Extensible Adaptive optics Real-time Toolkit (HEART) where new AO control features can be exercised on-sky ahead of deployment on a facility class instrument. In this paper, we present various analysis of the telemetry produced by HEART and its various wavefront-sensing arms that enable both open- and closed-loop operation including a closed-loop Shack-Hartmann wavefront sensor, a closed-loop pyramid wavefront sensor, and an open-loop Shack-Hartmann. Employing REVOLT's single-conjugate AO configuration, we look at extracting the Fried parameter and other atmospheric parameters from the telemetry and compare the results to an in-situ Ring Image Next Generation Scintillation Sensor (RINGSS) atmospheric seeing monitor and optical turbulence profiler. Finally, we discuss the AO s ystem's r ejection-transfer f unction and overall system's performance.
Research, Experiment, and Validation of Adaptive Optics with a Legacy Telescope (REVOLT) is a single conjugate adaptive optics system (SCAO) located on the 1.2-meter McKellar telescope at the Dominion Astrophysical Observatory (DAO), Victoria, Canada. REVOLT is used to perform on-sky testing of key adaptive optics (AO) technologies developed at NRC Herzberg Astronomy & Astrophysics (HAA). The REVOLT project successfully demonstrated closed-loop SCAO with the Herzberg Extensible Adaptive Realtime Toolkit (HEART) and First Light Imaging's C-Blue One detector. In this proceeding, we present a wavefront error budget analysis of REVOLT using results obtained on-sky, in a lab setting, and simulation. We find good agreement with the sum of expected error terms and the on-sky performance, and we comment on potential sources of additional wavefront errors and potential improvements to the system which may improve overall performance.
The Thirty Meter Telescope (TMT) will host three science instruments at first light: IRIS (InfraRed Imaging Spectrograph), WFOS (Wide Field Optical Spectrograph), and MODHIS (Multi-Objective Diffraction-limited High-resolution Infrared Spectrograph). IRIS is a workhorse imager and spectrograph coupled to the Narrow-Field InfraRed Adaptive Optics System (NFIRAOS) to exploit the gains possible when working at the diffraction limit on an extremely large telescope. It has an imager field of view of 34 by 34 square arcseconds, and the integral field spectrograph supports a variety of spaxel scales and fields of view at resolutions between 4000 and 10,000. MODHIS, also working behind NFIRAOS, is focused on exoplanet science will deliver precision radial velocity measurements at a spectral resolution of 100,000 for a single object. WFOS is the workhorse optical multi-object imaging spectrograph. It has an 8 by 3 square arcminute field of view and is capable of targeting almost 100 objects at once with resolutions between 1500 and 5000. In this paper, we present overviews of the technical capabilities of each of these instruments and show how those capabilities translate into meeting key TMT science requirements. Finally, we provide an update on the design progress of these three instruments.
We present the preliminary design for the configurable slit unit (CSU) for TMT's Wide Field Optical Spectrometer (WFOS) [1]. The design consists of 96 bar pairs that can create an arbitrary pattern of focal plane slits. The large number of motorized mechanisms to drive the bars into position requires a high reliance on off the shelf components to reduce cost and design effort. A prototype was completed that shows the selected components will likely meet requirements. The current design nearing completion as WFOS ramps into a preliminary design review in 2025.
The Thirty Meter Telescope will use a sophisticated adaptive optics system called NFIRAOS. This system utilizes two deformable mirrors conjugate to 0 km and 11.2 km to apply a Multi-Conjugate Adaptive Optics (MCAO) correction over a 2 arcminute field of view. DM0 and DM11 have 63 and 75 actuators across their respective diameters. To study the behavior of these mirrors, we have developed a low-cost, very high-order Shack-Hartmann Wavefront Sensor (WFS). We will use our WFS to calibrate the flatness of the DMs and measure the influence functions of the actuators. NFIRAOS is cooled to reduce the thermal emissivity of optical surfaces visible to the science detectors, so we will also measure the behaviour of the DMs in both warm and cold environments. As the cold chamber is prone to vibrations, a WFS is preferred to a phase-shifting interferometer. Our design was driven by the need to be able to evaluate the DM surface between the actuators, which led to the requirement of at least 248 sub apertures across the diameter. The largest commercially available Shack-Hartmann WFS has only 128 sub-apertures across the diameter, which is not enough to properly sample these DMs. Furthermore, the designed sensor is able to record the wavefront at 50 FPS (50 times per second) at full resolution. To fabricate this WFS, we used a commercial off-the-shelf CMOS detector, camera lens, and lens let array, which kept the total cost less than 20K USD. Here we present the design and performance characteristics of this device.
We present the current design of WFOS, a wide-field UV/optical (0.31-1.0 µm) imaging spectrograph planned for first-light on the TMT International Observatory 30 m telescope. WFOS is optimized for high sensitivity across the entire optical waveband for low-to-moderate resolution (R ∼ 1500-5000) long-slit and multi-slit spectroscopy of very faint targets over a contiguous field of view of 8′ .3×3 ′ .0 at the f/15 Nasmyth focus of TMT. A key design goal for WFOS is stability and repeatability in all observing modes, made possible by its gravity-invariant opto-mechanical structure, with a vertical rotation axis and all reconfigurable components moving only in planes defined by tiered optical benches parallel to the Nasmyth platform. WFOS's optics include a linear ADC correcting a 9′ diameter field, including both the science FoV and 4 patrolling acquisition, guiding, and wavefront sensing camera systems; a novel 2-mirror reflective collimator allowing the science FoV to be centered on the telescope optical axis; a dichroic beamsplitter dividing the collimated beam into 2 wavelength-optimized spectrometer channels (blue: 0.31-0.56 µm; red: 0.54-1.04 µm); selectable transmissive dispersers (VPH and/or VBG) with remotely configurable grating tilt (angle of incidence) and camera articulation that enable optimization of diffraction efficiency and wavelength coverage in each channel; all-refractive, wavelength-optimized f/2 spectrograph cameras, and UV/blue and red-optimized detector systems. The predicted instrumental through put of WFOS for spectroscopy averages > 56% over the full 0.31-1 µm range, from the ADC to the detector. When combined with the 30 m TMT aperture, WFOS will realize a factor of ∼20 gain in sensitivity compared to the current state of the art on 8-10 m-class telescopes.
HISPEC (High-resolution Infrared Spectrograph for Exoplanet Characterization) is an infrared (0.95 to 2.46 microns) cross-dispersed, R=100,000 single-mode fiber-fed diffraction-limited echellette spectrograph for the Keck II telescope's adaptive optics (AO) system. MODHIS (Multi-Objective Diffraction-limited High-resolution Infrared Spectrograph) shares similar specifications as HISPEC while being optimized for TMT's first-light AO system NFIRAOS. Keck-HISPEC (2025) then TMT-MODHIS will provide increasingly compelling science capabilities from exoplanet atmosphere characterization through both transit and direct high-contrast spectroscopy, to detection and mass measurements through infrared precision radial velocity (RV). The science cases include the precise RV measurements of stars orbiting the Galactic Center, Solar System studies, and the chemodynamical history of nearby dwarf galaxies and the galactic halo.
NFIRAOS is the first-light adaptive optics system for the Thirty Meter Telescope (TMT). It features a sub-cooled thermal enclosure (ENCL) operating at -30 degrees Celsius (˚C), which contains all of the opto-mechanics for the system. A unique entrance window system (NWIND) features a pair of windows separated by vacuum to allow light from the telescope to enter NFIRAOS, while precisely controlling the surface temperatures of the window optics to match the internal and external thermal environments of the enclosure. This ensures that convective currents are not created at the glass surfaces, which are both near the focal plane of the system. NWIND uses a set of multiple temperature controlled warm and cold radiative baffles positioned in the vacuum space between the optics to counteract and balance the radiative thermal load between the two optics, which are typically operated at +5˚C and -30˚C. Presented here are the requirements, design, and engineering of the NFIRAOS entrance window.
The Extremely Large Telescope and the Thirty Meter Telescope will use state of the art multiconjugate adaptive optics (MCAO) systems to obtain the full D4 advantage that their apertures can provide. However, to reach the full astrometric potential of these facilities for on-sky science requires understanding any residual astrometric distortions from these systems and find ways to measure and eliminate them. In this work, we use Gemini multiconjugate adaptive optic system (GeMS) observations of the core of NGC 6723 to better understand the on-sky astrometric performance of MCAO. We develop new methods to measure the astrometric distortion fields of the observing system, which probe the distortion at the highest possible spatial resolution. We also describe methods for examining the time-variable and static components of the astrometric distortion. When applied to the GeMS Gemini South Adaptive Optics Imager (GSAOI) data, we are able to see the effect of the field rotator at the subpixel level, and we are able to empirically derive the distortion due to the optical design of GeMS-GSAOI. We argue that the resulting distortion maps are a valuable tool to measure and monitor the on-sky astrometric performance of future instrumentation. Our overall astrometry pipeline produces high-quality proper motions with an uncertainty floor of 45 uas per year. We measure the proper motion dispersion profile of NGC 6723 from a radius of 10 arcsec out to 1 arcmin based on 12000 stars. We also produce a high-quality optical-near infrared color-magnitude diagram, which clearly shows the extreme horizontal branch and main-sequence knee of this cluster.
GIRMOS is an integral field spectrograph designed to operate behind the Gemini North Adaptive Optics system. Its four arms will run in open-loop mode, using the telemetry received from GNAO to reconstruct tomographically the turbulence along each direction. The application of open-loop correction has been shown to be challenging on other instruments, because of the inability to monitor in real time its effect on the observed target. To reduce the risks associated to the use of open-loop adaptive optics with GIRMOS, we test our calibration procedures on sky using REVOLT, the adaptive optics bench and imager for the 1.2m telescope at the Dominion Astrophysical Observatory in Victoria, Canada.
NFIRAOS, the Narrow Field Infrared Adaptive Optics System, is the first light AO System for the Thirty Meter Telescope (TMT). It performs wavefront correction in the near infrared spectrum using various optomechanical components operating under strictly controlled conditions. The NFIRAOS Optical Enclosure (ENCL) is designed to provide a housing that maintains an ideal clean sub-zero environment (-30 ±0.5 C) for such components. To manage this, the ENCL provides a multi-leveled control system that accurately manages the environment using low-level hardware control to ensure that internal systems are not subjected to environmental effects that may adversely affect operation, while coordinating with the telescope operation. We will analyze the aspects of the operational constraints to allow the ENCL Control System to communicate with low level sensors and controllers as well as with the high-level Controller management system to ensure all operational conditions are fully met.
IRIS is a diffraction-limited imaging spectrograph designed for first light of the Thirty Meter Telescope (TMT). It is fed Multi-Conjugate Adaptive Optics (MCAO)-corrected light from the Narrow-Field Infrared Adaptive Optics System (NFIRAOS). IRIS, however, is responsible for sensing the low order modes: tip, tilt, focus, and plate scale modes to which the NFIRAOS Laser Guide Star (LGS) Wavefront Sensors (WFSs) are blind. During the IRIS final design, we developed a noise-equivalent angle budget that included the optical throughput of the telescope, NFIRAOS and OIWFS, the detector pixel size, quantum efficiency, readnoise and excess shot noise, diffraction including optical aberrations, and sky and thermal backgrounds. The noise equivalent angle was calculated for the near-infrared star brightness corresponding to 50% sky coverage at the North Galactic Pole for an exposure time required to meet the overall TMT wavefront error budget. We present the trade studies, performance budgets and simulation results which drove the final design of the optics, mechanics and detectors of the IRIS OIWFS system.