MOSAIC is a wide-field spectrograph, combining multiple-object spectroscopy and integral field units, to cover the ELT focal plane with a field-of-view of 7.8 arcmin from the blue to the near-infrared, 390 to 1800nm. In the current Phase B design, AO is GLAO supported by four LGS in a fixed asterism and with multiple NGS. Although the GLAO correction is modest compared to other ELT instrumentation, the use of the integrated M4/M5 correction elements and the existing LGS allows for an efficient design which is outlined. MOSAIC GLAO will use the ELT PFS guide-probes to compensate for high- frequency tip/tilt errors, greatly relaxing the requirements on the instrumental NGS sensors. The Phase A architecture used the same pick-off mirrors as the IFU instruments to feed the NGS-WFS from anywhere in the focal plane, which was mandatory for the proposed MOAO design. The reduced performance requirements at Phase B allows us to take advantage, instead, of the four 2 arcmin diameter field-of-view through the LGS cutouts, arranged in a square pattern at an off-axis distance of 3.75 arcmin. In each LGS cutout, a wide-field-imager is implemented–alongside one LGS WFS–to acquire multiple NGS that supports both slow tip/tilt measurements, isolating instrument-Nasmyth flexure, solving for the astrometric distortion expected from errors in the ELT optical path, and supporting the alignment of MOS apertures with the field. The latter is a key requirement for MOSAIC, leading to 40mas accuracy in MOS aperture positioning and 40mas rotation displacement at the edge of the scientific field.
MOSAIC is an instrument for the Extremely Large Telescope (ELT). The instrument has started phase B, and apart from technical and financial requirements, MOSAIC has the additional requirement to investigate and minimise its environmental impact. The first step is to estimate the carbon footprint (and other effects) in a ‘Life Cycle Analysis’, for the instrument development up to Provisional Acceptance in Chile. This paper presents a preliminary analysis, aimed at identifying potential contributors to environmental impact. Investigated contributors are: materials, Full-Time-Equivalents, travel, and transport of the instrument. Not yet investigated (due to lack of information or certainty) are: electronics, test facilities and prototyping. Uncertainty in input data and conversion factors leads to error bars of a factor 2 or larger. Therefore, the outcome of the analysis can be used for internal comparison of contributors only, and it should not be used for comparison to other instruments or disciplines.
MOSAIC is the Muti-Object Spectrograph for the 39m ESO Extremely Large Telescope. The instrument development has recently been reorganized in different channels to be implemented progressively. The Laboratoire d’Astrophysique de Marseille (LAM) is in charge of the instrument “Assembly, Integration, Test and Verification (AIT/V)” phases. AITV for AO instruments, in laboratory as at the telescope, always represent numerous technical challenges. We already started the preparation and planning for the instrument level AIT activities, from identification of needs, challenges, risks, to defining the optimal AIT strategy.
In this paper, we present the state of this study, discuss a new approach with distributed AIT activities and controlled remotely over different sites. We describe AIT/V scenarios with phased implementation, starting with the Front-End and Visible channels AIT phases. We also show our capacity, experience (several MOS instruments, ELT HARMONI) and expertise to lead the instrument MOSAIC AIT/V activities both in Europe and at the telescope in Chile.
MOSAIC* is the multi-object spectrograph (MOS) for the ESO 39m European Extremely Large Telescope (ELT) approved to enter phase B at the of beginning 2023. MOSAIC combines visible and near-infrared channels, from resolved stars up to the most distant galaxies, with multi-object and multi-integral field spectroscopy capabilities. The NIR-spectrograph (130K-90K) is one sub-system of the NIR-channel, led by the Universidad Complutense de Madrid (UCM, Spain). The NIR Spectrograph (NIRSPEC) comprises 2 identical spectrographs, each one equipped with Teledyne H4RG science detectors (4kx4k, 15 μm pixels). Each spectrograph operates at 130K (with detectors at 90K) and covers the 2 observing bands J (1 – 1.38 μm) and H (1.43 – 1.85 μm in low-resolution mode and 1.52 – 1.65 μm in high-resolution mode). This paper presents the optical design of the NIRSPEC.
MOSAIC is the Multi-Object Spectrograph (MOS) for the 39m Extremely Large Telescope (ELT) of the European Southern Observatory (ESO), with unique capabilities in terms of multiplex, wavelength coverage and spectral resolution. It is a versatile multi-object spectrograph working in both the Visible and NIR domains, designed to cover the largest possible area (∼40 arcmin2) on the focal plane, and optimized to achieve the best possible signal-to-noise ratio on the faintest sources, from stars in our Galaxy to galaxies at the epoch of the reionization. In this paper we describe the main characteristics of the instrument, including its expected performance in the different observing modes. The status of the project will be briefly presented, together with the positioning of the instrument in the landscape of the ELT instrumentation. We also review the main expected scientific contributions of MOSAIC, focusing on the synergies between this instrument and other major ground-based and space facilities.
MOSAIC is the multi-object spectrograph (MOS) for the ESO 39m European Extremely Large Telescope (ELT) approved to enter phase B beginning 2023. MOSAIC combines visible and near-infrared channels, from resolved stars up to the most distant galaxies, with multi-object and multi-integral field spectroscopy capabilities. The NIRspectrograph (130K-90K) is one sub-system of the NIR-channel, led by the Universidad Complutense de Madrid (UCM, Spain). It includes four camera modules delivered by the Laboratoire d’Astrophysique de Marseille (LAM, France) and equipped with Teledyne H4RG science detectors (4kx4k, 15 μm pixels). The four modules distribute two identical cryogenic benches ensuring, on each, the spectral coverage of the two observing bands J (0.95 – 1.34 μm) and H (1.43 – 1.80 μm in LR mode and 1.52 – 1.63 μm in HR mode). This paper presents the design of a cryogenic NIR camera prototype based on an athermal concept and details the ongoing AIT development for verification in the 0.95 – 1.34 μm domain in relevant environment (ESO TRL5).
MOSAIC, the multi-object spectrograph (MOS) for the ESO 39m European Extremely Large Telescope (ELT), will combine visible and near-infrared observations with multi-object and multi-integral field spectroscopy capabilities. It will cover a wide panel of topics, from resolved stars up to the most distant galaxies. In the frame of the NIR spectrograph unit realization led by the Laboratoire d’Astrophysique de Marseille (LAM), this paper presents the ongoing development of a cryogenic (90-130 K) NIR camera prototype tested in the 0.77-1.063 µm wavelengths (I band) detailing the opto-mechanical design and the integration and verification strategies in accordance with validation in relevant environment (ESO TRL5).
The Maunakea Spectroscopic Explorer (MSE) is a 10m-class, wide-field (1.5 sq. degree) and high-multiplex (< 3000 fibers) spectroscopic facility that will replace the 3.6m Canada-France-Hawaii Telescope. With backend spectrographs operating at low (R ~ 3000), moderate (R ~ 6000) and high (R ~ 20/40 k) spectral resolution across the 0.36 – 1.8 µm range, MSE will be poised to address a variety of science questions among which the nature of dark matter, the origin of the elements in the periodic table, the mass of the neutrino, whilst enabling a new era of rapid-response and time-domain astronomy. This paper is a status report of the MSE Low Moderate Resolution spectrograph design, from the Conceptual Design Review (CoDR) towards the Preliminary Design Phase (PDP).
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