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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 2500 deg2 integral-field survey over a 3.5 year period from Las Campanas Observatory (LCO) in Chile. The facility comprises four small (16 cm) telescopes that deliver science, calibration, and spectro-photometric light to three bench-mounted multi-object spectrographs, designed and build by Winlight Systems. All four telescopes will be equipped with a microlens array integral-field unit (IFU) to slice the focal plane into 35–arcsec large spatial elements while maintaining near-telecentric coupling at the fiber input. The science IFU comprises 1801 fibers, additional 143 fibers are allocated for sky-background and spectro-photometric calibration, totaling 1944 fibers. Each spectrograph will be fed by 648 fibers, which are reformatted into a linear array, forming the entrance slit. In this paper, we present the opto-mechanical design of the LVM-LCO fiber cable system.

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.

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 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."

The NEID spectrograph is a R $\sim$ 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 \cms{}. 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., Comment: Conference Proceeding from SPIE Astronomical Telescopes + Instrumentation (2020): 12 pages

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.

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 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.

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., SPIE Astronomical Telescopes + Instrumentation 2020, Ground-based and Airborne Instrumentation for Astronomy VIII