The second generation of ELT instruments includes an optical-infrared high-resolution spectrograph, ANDES, ArmazoNes high Dispersion Echelle Spectrograph. It covers a wide spectral range that goes from 0.4 to 1.8μm (goal 0.35 to 2.4μm). A common model of detector is planned for the two visible spectrographs RIZ and UBV. A total of five detectors will cover the latter spectral range. A common detector unit design has been developed based on ELT's standard components and inspired by the previous successful detector units designed for HARPS and ESPRESSO. It consists of a 9k x 9k CCD detector, a differential vacuum cryostat that keeps the detector in its dedicated vacuum chamber and a cryocooler that cools down the detector to minimize the dark noise. The required temperature, mechanical and pressure stabilities drive the design of the detector unit.
The ESO/ELT ANDES (ArmazoNes high Dispersion Echelle Spectrograph) project successfully completed the system architecture review and is currently finalizing its preliminary design phase. ANDES is the high-resolution spectrograph for the ELT (ESO Extremely Large Telescope) capable of reaching a resolution of R ~ 100,000 simultaneously, in a wavelength range between 0.35 -2.4 µm (goals included), characterized by high-precision and extreme calibration accuracy suitable to address a variety of flagship scientific cases across a wide range of astronomical domains. To fulfill the required specifications the proposed design adopts a modular approach where the instrument is split in four individual spectrographs, each fiber-fed, and thermally and vacuum stabilized. A dedicated front-end which host a single conjugated adaptive optics module, collects either the light from the telescope or from a calibration unit feeding in turn the individual spectrographs. To master the described complexity the same modularity is reflected also at the project management level: each of the 9 subsystems (counting also the software as a standalone subsystem) is under direct responsibility of different teams coordinated by the ANDES project office. The high distribution and the large community involvement, consisting of 24 institutes from 13 countries, represent certainly a challenge from the project management point of view. In this paper we present the project management approach we envisaged to master successfully all the ANDES project phases from the finalization of the preliminary design up to commissioning on-sky; in particular we will describe in detail the risk management and PA/QA activities we have foreseen to assure appropriate risk mitigation and an overall high-quality standard required for the ANDES project.
4MOST is a new high-multiplex, wide-field spectroscopic survey facility under construction for ESO's 4m-VISTA telescope at Paranal, Chile. Its key specifications are: a large field of view of 4.4 square degrees, a high multiplex fibre positioner based on the tilting spine principle positioning 2436 science fibres, 1624 fibres going to two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20,000). The instrument is entirely completed and is being shipped to Paranal Observatory, Chile in the first few months of 2024. Commissioning will take place summer 2024 with full operations expected to start early 2025. An overview will be given of instrument capabilities, the planned, and the unique operational scheme of 4MOST.
The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of ∼100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 μm with the goal of extending it to 0.35-2.4 μm with the addition of an U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allows ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coudé room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states.
The RIZ & UBV visible spectrographs of the ANDES instrument, which are foreseen to be installed at the Extremely Large Telescope, require to be under a very stable high vacuum and at an extremely stable temperature of 1mK to reach the radial velocity goal of 10cm/s RMS over a 10-year period. The baseline design, integration and first analyses of the 5.5t aluminum vacuum tank, vacuum system, and the thermal enclosure of the two-room temperature spectrographs are presented in this paper. A very analogous configuration is proposed for both instruments in view of their similarities. In addition, this article addresses the finite rigidity of the Nasmyth platform and its consequences on the instrument design together with a potential collaborative multi-CAD Product Design Management platform description.
We present the design of the ANDES UBV module, the bluest spectrograph of the ANDES instrument. It is a fiber-fed high resolution, high stability spectrograph, which will be installed on the ELT-Nasmyth platform to minimize blue fibre losses from the focal plane to the spectrograph. In this paper we present the status of development of the spectrograph, its optical design, and auxiliary devices like exposure meter and leveling system, at the preliminary design stage. As stability is the prime design driver, a thermal enclosure is provided to keep temperature of the optical train stable at ambient conditions, and the pressure is kept constant at high vacuum level. The science, sky background and simultaneous calibration light is fed to the spectrographs via fiber bundles of 66 fibres, which are arranged in a straight row forming the spectrograph slit.
We present here the preliminary design of the RIZ module, one of the visible spectrographs of the ANDES instrument. It is a fiber-fed high-resolution, high-stability spectrograph. Its design follows the guidelines of successful predecessors such as HARPS and ESPRESSO. In this paper we present the status of the spectrograph at the preliminary design stage. The spectrograph will be a warm, vacuum-operated, thermally controlled and fiber-fed echelle spectrograph. Following the phase A design, the huge etendue of the telescope will be reformed in the instrument with a long slit made of smaller fibers. We discuss the system design of the spectrographs system.
4MOST is a new high-multiplex, wide-field spectroscopic survey facility under construction for ESO's 4m-VISTA telescope at Paranal, Chile. Its key specifications are: a large field of view of 4.4 square degrees, a high multiplex fibre positioner based on the tilting spine principle that positions 2436 science fibres in the focal surface of which 1624 fibres go to two low-resolution optical spectrographs (R = λ/Δλ ~ 6500) and 812 fibres transfer light to the high-resolution optical spectrograph (R ~ 20,000). Currently, almost all subsystems are completed and full testing in Europe will be finished in spring 2023, after which 4MOST will be shipped to Chile. An overview is given of instrument construction and capabilities, the planned science of the consortium and the recently selected community programmes, and the unique operational scheme of 4MOST.
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