SPIRou @CFHT: integration and performance of the cryogenic near infra-red spectrograph unit
Résumé
SPIRou is an innovative near infra-red echelle spectropolarimeter and a high-precision velocimeter for the 3.6 m Canada-France-Hawaii Telescope (CFHT - Mauna Kea, Hawaii). This new generation instrument aims at detecting planetary worlds and Earth-like planets of nearby red dwarfs, in habitable zone, and studying the role of the stellar magnetic field during the process of low-mass stars / planets formation. The cryogenic spectrograph unit, cooled down at 80 K, is a fiber fed double-pass cross dispersed echelle spectrograph which works in the 0.98-2.40 μm wavelength range, allowing the coverage of the YJHK bands in a single exposure. Among the key parameters, a long-term thermal stability better than 2 mK, a relative radial velocity better than 1 m.s -1 and a spectral resolution of 70K are required. After 1 year of assembly, integration and tests at IRAP/OMP (Toulouse, France) during 2016/2017, SPIRou was then shipped to Hawaii and completely re-integrated at CFHT during February 2018. A full instrument first light was performed on 24th of April 2018. The technical commissioning / science validation phase is in progress until June 2018, before opening to the science community. In this paper, we describe the work performed on integration and test of the opto-mechanical assemblies composing the spectrograph unit, firstly in-lab, in Toulouse and then on site, at CFHT. A review of the performances obtained in-lab (in 2017) and during the first on-sky results (in 2018) is also presented.