In the GRAVITY+ project, GRAVITY is presently undergoing a series of upgrades to enhance its performance, add wide field capability and thereby expand its sky coverage. Some aspects of these improvements have already been implemented and commissioned by the end of 2021, making them accessible to the community. The augmentation of sky coverage involves increasing the maximum angular separation between the celestial science object and the fringe tracking object from the previous 2 arcseconds (limited by the field of view of the VLTI) to 20 – 30 arcseconds (constrained by atmospheric conditions during observation). Phase 1 of GRAVITY+ Wide utilizes the earlier PRIMA Differential Delay Lines to compensate for the optical path length variation between the science and fringe tracking beams throughout an observation. In phase 2, we are upgrading the existing beam compressors (BC) to integrate optical path length difference compensation directly into the BC. This modification eliminates five optical reflections per beam, thereby enhancing the optical throughput of the VLTI–GRAVITY system and the bandwidth of the vibrational control. We will present the implementation of phase 2 and share preliminary results from our testing activities for GRAVITY+ Wide.
MICADO, a Multi-AO Imaging Camera for Deep Observations, is a first light imager for the European Large Telescope (ELT). It is being designed and built by a consortium of partners from 6 different countries across Europe and led by the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching. The European Southern Observatory (ESO) is responsible for delivering the near infrared detector subsystem to the instrument. This subsystem includes nine Hawaii-4RG-15 (H4RG-15) near infrared detectors (2.5μm cut-off) mounted in a compact 3x3 mosaic at the heart of the instrument. They will operate at a nominal temperature of 82K using an array of cryogenic preamplifiers located at the back of the focal plane plate, close to the detectors. This paper presents an overview of this detector subsystem, including the measured performance of two of the H4RG-15 science detectors already characterised in a custom-built test facility at ESO. Special readout modes have been developed for the instrument and for AO corrections to one of the ELT mirrors and these are described. The design of the focal plane, its thermal analysis and the focal plane flatness measurement system being setup at ESO is also presented. This paper also provides a brief description of the new detector controllers (NGCII) being developed at ESO for all the ELT and future VLT (Very Large Telescope) science detector systems and presents the specific controller configuration which must be implemented for the MICADO detectors.
MICADO is a first light instrument for the Extremely Large Telescope (ELT), set to start operating later this decade. It will provide diffraction limited imaging, astrometry, high contrast imaging, and long slit spectroscopy at near-infrared wavelengths. During the initial phase operations, adaptive optics (AO) correction will be provided by its own natural guide star wavefront sensor. In its final configuration, that AO system will be retained and complemented by the laser guide star multi-conjugate adaptive optics module MORFEO (formerly known as MAORY). Among many other things, MICADO will study exoplanets, distant galaxies and stars, and investigate black holes, such as Sagittarius A* at the centre of the Milky Way. After their final design phase, most components of MICADO have moved on to the manufacturing and assembly phase. Here we summarize the final design of the instrument and provide an overview about its current manufacturing status and the timeline. Some lessons learned from the final design review process will be presented in order to help future instrumentation projects to cope with the challenges arising from the substantial differences between projects for 8-10m class telescopes (e.g. ESO’s VLT) and the next generation Extremely Large Telescopes (e.g. ESO’s ELT). Finally, MICADO's expected performance will be discussed in the context of the current landscape of astronomical observatories and instruments. For instance, MICADO will have similar sensitivity as the James Webb Space Telescope (JWST), but with six times the spatial resolution.
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