MOSAIC @ELT: overview of the MAIT strategy of an athermal camera prototype for the NIR-spectrograph

Abstract

MOSAIC is the multi-object spectrograph (MOS) for the ESO 39m European Extremely Large Telescope (ELT). The instrument is progressing in phase B2 since 2025. It presents multi-object and multi-integral field spectroscopy capabilities and combines visible and near-infrared channels, to observe from resolved stars up to the most distant galaxies. The two NIR-spectrographs (130K-80K) are part of the NIR-channel system led by the Universidad Complutense de Madrid (UCM, Spain). The current design includes four camera modules delivered by the Laboratoire d’Astrophysique de Marseille (LAM, France), two per spectrograph, ensuring the spectral coverage of the two observing bands J (0.95-1.34 μm) and H (1.43-1.80 μm). Each camera is equipped with Teledyne H4RG detectors (4kx4k, 15 μm pixels). This paper presents the MAIT strategy and development to verify the athermal concept of a cryogenic NIR camera prototype in relevant environment (ESO TRL5) and to anticipate the MAIT plan of the NIR science cameras.