The Canadian Hydrogen Observatory for Radio-transient Detectors (CHORD) will consist of 640 six-meter diameter antennas made of fiberglass composite material. The antennas will be fabricated and assembled at the Dominion Radio Astrophysical Observatory (DRAO) in Kaleden, BC, Canada, managed by the National Research Council of Canada (NRC). NRC has developed composite based single piece reflector technology over the past decade. A high degree of dimensional repeatability is key for CHORD to meet its scientific goals. This begins by manufacturing highly stable and repeatable dish molds. Subsequently, highly repeatable dishes are manufactured, components are assembled, and antennas are precisely positioned in the CHORD array. In this paper we present the antenna mechanical system, production of the antenna, top-level requirements, error definitions and verification plan, performance verification plan, and quality management plan. Since the antennas are made of composites, formulating an error budget is critical to keep track of the error allocations due to process induced errors, tooling and mold errors, and surface distortions due to gravity, wind and temperature variation. In addition, an overall pointing budget has been prepared to allocate the effect of mechanical misalignment, wind, foundation movement and other sources, etc. A Monte Carlo simulation of 1000 antennas provided the error stack up and expected precision values. A detailed verification plan is presented. Finally, the quality engineering plans are in place so that the manufacturing facility can ensure the production of the repeatable antennas through a quality assurance program. An acceptance sampling of the antennas will be conducted for metrology-based verification. A robust quality management plan is also in place to safeguard repeatability of the antenna production. The antennas will be accompanied by production data-cards, which enlist the critical configuration and process data about the antenna production and assembly operations. At the end of the pipeline, these antennas will go through verifications and acceptance tests to validate that performance requirements are met.

The Gemini High-resolution Optical SpecTrograph (GHOST) is the newest high-resolution spectrograph to be developed for a large-aperture telescope, recently deployed and commissioned at the Gemini-South telescope. In this paper, we present the first science results from the GHOST spectrograph taking during its commissioning runs. We have observed the bright metal-poor benchmark star HD 122563, along with two stars in the ultrafaint dwarf galaxy Reticulum II (Ret ii ), one of which was previously identified as a candidate member, but did not have a previous detailed chemical abundance analysis. We find that this candidate (GDR3 0928) to be a bona fide member of Ret ii , and from a spectral synthesis analysis it is also revealed to be a CEMP- r star, with significant enhancements in several light elements (C, N, O, Na, Mg, and Si), in addition to featuring an r -process enhancement like many other Ret ii stars. The light-element enhancements in this star resemble the abundance patterns seen in the CEMP-no stars of other ultrafaint dwarf galaxies, and are thought to have been produced by an independent source from the r -process. These unusual abundance patterns are thought to be produced by faint supernovae, which may be produced by some of the earliest generations of stars.

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.

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 Support Structure for the Thirty Meter Telescope (TMT) Infrared Imaging Spectrograph (IRIS) consists of 18 carbonfiber reinforced polymer (CFRP) struts, a CFRP ring and a metal interface frame. This ultra-stiff, lightweight structure suspends the five-ton IRIS Science Cryostat and Rotator below the Narrow Field Infrared Adaptive Optics System (NFIRAOS). Through comprehensive design and analysis driven by requirements for stiffness, optical alignment, adjustability, manufacturability, weight and space, much headway was made to bring this design to fruition. This work presents the current state of design, including material down-selection, adjuster design and strategies for fabrication, alignment and testing. It summarizes methodologies and simulation results examining stiffness, seismic and thermal loads and transmission of vibration between NFIRAOS and IRIS. A prototype strut is being developed and will undergo dynamic mechanical testing to characterize its performance.

The first light instrument on the Thirty Meter Telescope (TMT) project will be the InfraRed Imaging Spectrograph (IRIS). The IRIS On-Instrument Wavefront Sensor (OIWFS) provides diffraction limited wavefront sensing – in both tip/tilt and tip/tilt/focus modes – to NFIRAOS (Narrow Field InfraRed Adaptive Optics System). As part of the final design phase, we have further developed the optical and mechanical designs. We present recent changes to the optical design and the resulting performance and tolerance analysis. Changes include decreasing the field of view to 1.5×1.5 arcseconds (square) and moving the field lens to reduce vignetting of the science image. The mechanical design is being updated with more detail for the optical mounts. We present here example mounts and associated analyses and our plans for future prototyping.

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.

NFIRAOS (Narrow-Field InfraRed Adaptive Optics System) will be the first-light multi-conjugate adaptive optics system for the Thirty Meter Telescope (TMT). NFIRAOS houses all of its opto-mechanical sub-systems within an optics enclosure cooled to precisely -30 degrees C in order to improve sensitivity in the near-infrared. It supports up to three client science instruments, including the first-light InfraRed Imaging Spectrograph (IRIS). Powering NFIRAOS is a Real Time Controller that will process the signals from six laser wavefront sensors, one natural guide star pyramid WFS, up to three low-order on-instrument WFS and up to four guide windows on the client instrument's science detector in order to correct for atmospheric turbulence, windshake, optical errors and plate-scale distortion. NFIRAOS is currently preparing for its final design review in late June 2018 at NRC Herzberg in Victoria, British Columbia in partnership with Canadian industry and TMT.

The ALMA Observatory is under construction at 5000 m above sea level on the Chajnantor plateau located in the Atacama Desert, Chile. When complete it will be comprised of 66 parabolic reflector antennas that can be configured in various arrays using a subset of 192 different stations with baselines from 15 to 16,000 m. The Antenna Group in the ALMA Department of Engineering is responsible for maintenance of the antenna mechanical, control and structural systems, antenna relocations and mechanical aspects of astronomical instrumentation exchanges. The large number of antennas, expanse, elevation, weather conditions of the Array Operation Site (AOS) and its distance from the Operations Support Facility (OSF) will make operations and maintenance for the Antenna Group a challenge. Currently, approximately half of the antennas are in place at the AOS and the first period of Early Science is underway. Operational strategies and specialized equipment developed for preventive and corrective maintenance, array reconfiguration and weather event response are being put to the test and revised based on real experience. This paper explains the operational environment, the constraints it imposes, some of the strategies and specialized equipment being developed to reduce reaction time and resources needed to maintain the array and maximize availability for science operations.