We introduce MOSES, the new High-Resolution Echelle Spectrograph designated for the 1.2m MONET telescope at McDonald Observatory, Texas, USA. The science drivers are radial velocity experiments and activity monitoring in Sun-like stars. Set for installation in the final quarter of 2025, MOSES features a white pupil design and aims for a spectral resolution greater than 80,000 over the 380-680 nm wavelength range. It incorporates a pixel sampling rate of 3.5 and uses two fibers to facilitate a simultaneous calibration mode. Encased within a vacuum vessel and operating in a temperature-stabilized environment, MOSES is expected to achieve a radial velocity precision below 2 m/s, aided by a Fabry-Perot etalon calibration system. This paper outlines the implementation of the fiber injection unit, the optical layout of the spectrograph, and the present status of the various subsystems under development.

We report on the design of 2ES (Second Earth Initiative Spectrograph): a new fiber-fed, high-resolution, high-precision radial velocity echelle spectrograph for the 2.2m ESO/MPG telescope in Chile, which will cover the visible wavelength range similar to 370nm to 850nm with a resolution of 120, 000. 2ES will be dedicated to a >5-year observing program with access to the majority (2/3) of the telescope time with the goal of discovering temperate terrestrial Earth-mass planets in the habitable zone around the bright solar-type stars. To achieve this goal, 2ES aims for ultra-high instrumental radial-velocity precision and an observing strategy that involves high-cadence observation of the brightest Sun-like stars in the Southern Hemisphere. Here, we present an overview of the project, its observation strategy, the optical design as well as the opto-mechanical concepts and calibration strategies to achieve the required instrument stability.

Three mirror anastigmatic telescope designs offer excellent imaging performance in a compact optical structure. The introduction of a fourth, fold mirror allows straightforward access to the image surface of the telescope at a Nasmyth position where instrumentation can be located and easily exchanged. The design presented here is of a 14-meter diameter primary providing a 1.5 square degree field of view with an f/4 focus to a pupil-centric image surface. Two fused silica lenses serve as an atmospheric dispersion compensator, a third field lens forms a large radius pupil-centric image. The optical design gives polychromatic (360-1800 nm) encircled energy diameters (EED) of greater than 80% within 0.25 arc-second diameters across the full field at Zenith. Excellent monochromatic image performance extends through and redward of the K-band (2320 nm). The flat fold mirror, located at a pupil, could be upgraded to an adaptive mirror for image correction and/or GLAO. Image performance is given. We believe that this design offers a very powerful, versatile, and scientifically viable facility suitable for the next generation of ground-based facilities for fiber spectroscopy (~18,000 probes), multi-slit spectroscopy, IFU spectroscopy, and imaging.

The Maunakea Spectroscopic Explorer (MSE) will target sources down to mAB = 24 with a signal to noise ratio > 1 from the near UV to H-band. Among MSE’s many science goals, this will allow the efficient spectroscopic follow-up of large imaging surveys anticipated from new facilities such as the Rubin Observatory. Given broadband AR coatings currently feasible for large optics, this poses a unique challenge in terms of controlling contamination from optical ghost reflections. We present exploratory work to identify telescope designs with optical ghost levels that satisfy the observational thresholds required for MSE. We also report on an initial estimate of scattering from the optics that indicates that it will have a minor impact on the accessible sky, does not drive the telescope design selection, but must be accounted for in science/sky fiber placement. The outcome of these studies is that a range of telescope configurations exist that allow MSE’s target sensitivity to be reached without limitation from optical ghosts or scattering from the optics.

We describe the camera articulation prototype (CAP) for the Giant Magellan Telescope Multi-object Astronomical and Cosmological Spectrograph (GMACS), which is a wide field, multi-object, moderate-resolution, optical spectrograph of the Giant Magellan Telescope (GMT). The GMACS will have the Camera and Grating Articulation System (CGAS) which has two independent cameras and grating modules. The grating angles and the camera angles can be changed to adjust the dispersed light bands on the detector. The electronics components of this system include motors with encoder, pneumatic brakes, and limit switches. We demonstrate how to control the camera angles using a prototype that is designed for the camera articulation controller as a miniature model of the GMACS. The prototype was built with commercially-available extruded aluminum struts and 3D-printed parts and includes two motors with encoders. The prototype was produced quickly and inexpensively, but replicates all functions of the camera articulation mechanism in GMACS. We have developed the control package for the prototype that will be one of the GMACS Device Control System (DCS). The software is designed by the Agile development process and SysML, and developed using Visual C++ on Windows OS. This software has five major control functions: power, homing, resolution mode changing, limit detection, and emergency process. The limit detection is implemented by setting up the limit angle range in the software, because the limit switches are not included in the prototype. We present the demonstration result and discuss the details of the communication route about data flow between high-end user software and hardware components.

The 4-meter Multi-Object Spectroscopic Telescope (4MOST) is a wide-field, high-multiplex spectroscopic survey facility under development for the Visible and Infrared Survey Telescope for Astronomy (VISTA) of the European Southern Observatory (ESO). The 4MOST Wide Field Corrector and Atmospheric Dispersion Corrector (ADC) lenses have been manufactured and tested at KiwiStar Optics, New Zealand. The two ADC wedged doublets form a Risley Prism Pair; are both 650 mm in diameter and relatively thin; and have been cemented using Sylgard 184 silicone elastomer. The cementing procedure and its challenges are reported here. Interferometric measurements of the single surfaces, glass blanks and the finished doublets have been compared in order to assess the effect of the cementing process on the final surface figures of the doublets before and after positioning in their cells.

The Giant Magellan Telescope Multi-object Astronomical and Cosmological Spectrograph (GMACS) is a first light instrument for the Giant Magellan Telescope (GMT). It will provide multi-object spectroscopy in wide wavelength coverage and wide field of view. The scientific objectives include exoplanet atmospheres, star formation and chemical evolution studies, galaxy assembly histories, and intergalactic medium tomography. The optical layouts are optimized to have high throughput in the natural seeing limit. In this presentation, we report the current status of the instrument development.

We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = \lambda/\Delta\lambda \sim 6500$), and 812 fibres transferring light to the high-resolution spectrograph ($R \sim 20\,000$). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA’s unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA’s robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph’s intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional “sum-of-Gaussians” instrumental profile: 1.8 m s−1 over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.

We describe the latest optomechanical design of GMACS, a wide-field, multi-object, moderate-resolution optical spectrograph for the Giant Magellan Telescope (GMT). Specifically, we discuss the details of the structure, mechanisms, optical mounts and deflection tracking/compensation as well as the requirements and considerations used to guide the design. We also discuss GMACS’s interfaces with GMT and other instruments.

We present a preliminary conceptual optical design for GMACS, a wide field, multi-object, optical spectrograph currently being developed for the Giant Magellan Telescope (GMT). We include details of the optical design requirements derived from the instrument scientific and technical objectives and demonstrate how these requirements are met by the current design. Detector specifications, field acquisition/alignment optics, and optical considerations for the active flexure control system are also discussed.

We present the current optical design of GMACS, a multi-object wide field optical spectrograph currently being developed for the Giant Magellan Telescope, a member of the emerging generation of Extremely Large Telescopes (ELTs). Optical spectrographs for ELTs have unique design challenges and issues. For example, the combination of the largest practical field of view and beam widths necessary to achieve the desired spectral resolutions force the design of seeing limited ELT optical spectrographs to include aspheric lenses, broadband dichroics, and volume phase holographic gratings - all necessarily very large. We here outline details of the collimator and camera subsystems, the design methodology and trade-off analyses used to develop the collimator subsystem, the individual and combined subsystem performances and the predicted tolerances.

We describe the optical design of GMACS, a multi-object wide field optical spectrograph currently being developed for the Giant Magellan Telescope (GMT). Optical spectrographs for the emerging generation of Extreme Large Telescopes (ELTs) have unique design issues. For example, the combination of both the largest field of view practical and beam widths achieving the desired spectral resolutions force the design of seeing limited ELT optical spectrographs to include large refractive elements, which in turn requires a compromise between the optical performance, manufacturability, and operability. We outline the details of the GMACS optical design subsystems, their individual and combined optical performance, and the preliminary flexure tolerances. Updates to the detector specifications, field acquisition/alignment optics, and optical considerations for active flexure control are also discussed. The resulting design meets the technical instrument requirements generated from the GMACS science requirements, is expected to satisfy the available project budget, and has an acceptable level of risk for the subsystem manufacture and assembly.

We describe the optical design of GMACS, a multi-object wide field optical spectrograph currently being developed for the Giant Magellan Telescope (GMT). Optical spectrographs for the emerging generation of Extreme Large Telescopes (ELTs) have unique design issues. For example, the combination of both the largest field of view practical and beam widths achieving the desired spectral resolutions force the design of seeing limited ELT optical spectrographs to include large refractive elements, which in turn requires a compromise between the optical performance, manufacturability, and operability. We outline the details of the GMACS optical design subsystems, their individual and combined optical performance, and the preliminary flexure tolerances. Updates to the detector specifications, field acquisition/alignment optics, and optical considerations for active flexure control are also discussed. The resulting design meets the technical instrument requirements generated from the GMACS science requirements, is expected to satisfy the available project budget, and has an acceptable level of risk for the subsystem manufacture and assembly.

An important tool for the development of the next generation of extremely large telescopes (ELTs) is a robust Systems Engineering (SE) methodology. GMACS is a first-generation multi-object spectrograph that will work at visible wavelengths on the Giant Magellan Telescope (GMT). In this paper, we discuss the application of SE to the design of next-generation instruments for ground-based astronomy and present the ongoing development of SE products for the GMACS spectrograph, currently in its Conceptual Design phase. SE provides the means to assist in the management of complex projects, and in the case of GMACS, to ensure its operational success, maximizing the scientific potential of GMT.

Hanle echelle spectrograph (HESP) is a high resolution, bench mounted, fiber-fed spectrograph at visible wavelengths. The instrument was recently installed at the 2m Himalayan Chandra Telescope (HCT), located at Indian Astronomical Observatory (IAO), Hanle at an altitude of 4500m. The telescope and the spectrograph are operated remotely from Bangalore,(similar to 3200km from Hanle), through a dedicated satellite link. HESP was designed and built by Kiwi Star Optics, Callaghan Innovation, New Zealand. The spectrograph has two spectral resolution modes (R=30000 & 60000). The low resolution mode uses a 100 micron fiber as a input slit and the high resolution mode is achieved using an image slicer. An R2 echelle grating, along with two cross dispersing prisms provide a continuous wavelength coverage between 350-1000nm. The spectrograph is enclosed in a thermally controlled environment and provides a stability of 200m/s during a night. A simultaneous thorium-argon calibration provides a radial velocity precision of 20m/s. Here, we present a design overview, performance and commissioning of the spectrograph.

We discuss the latest developments of a spectrograph for the Giant Magellan Telescope. The instrument is designed to provide high throughput, moderate resolution, optical spectra for the telescope and be capable of flexible and rapid reconfiguration. The focal plane can be populated with custom slit masks or multiple fibers, allowing for observations of multiple objects simultaneously.

We describe the current electronics prototypes for the Flexure Compensation System (FCS) and the Slit Mask Exchange Mechanism (SMEM) for GMACS, a wide-field, multi-object, moderate-resolution optical spectrograph for the Giant Magellan Telescope (GMT). We discuss the details of the FCS and SMEM prototypes, how the prototypes relate to the preliminary conceptual designs of these systems, and what information the prototypes give that can be applied to the final design, as well as the possible next steps for each prototype.