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First light of NIRPS, the near-infrared adaptive-optics assisted high resolution spectrograph for the ESO 3.6m

F. Wildi, F. Bouchy, R. Doyon, N. Blind, L. Genolet, M. Sordet, A. G. Segovia Milla, N. Grieves, L. Malo, E. Artigau, J. St-Antoine, P. Vallée, J. L. Rasilla, F. Gracia Temich, A.-S. Poulin-Girard, D. Brousseau, D. Sosnowska, V. Reshetov, F. Baron, S. Thibault, S. Bovay, Y. Frensch, G. Lo Curto, N. Hubin, G. Zins, C. Peroux, A. Cabral

NIRPS is an infrared precision Radial Velocity (pRV) spectrograph covering the range 950 nm-1800 nm. NIRPS uses a high-order Adaptive Optics (AO) system to couple the starlight into a fiber corresponding to 0.4" on the sky as efficiently or better than HARPS or ESPRESSO couple the light in a 1.0" fiber. This allows the spectrograph to be very compact, more thermally stable, and less costly. Using a custom tan(θ)=4 dispersion grating in combination with a start-of-the-art Hawaii4RG detector makes NIRPS very efficient with complete coverage of the YJH bands at just under 100 000 resolution. On the ESO 3.6-m telescope, NIRPS and HARPS are working simultaneously on the same target, building a single powerful high-resolution, high-fidelity spectrograph covering the 0.37-1.8 µm domain. NIRPS will complement HARPS in validating Earth-like planets found around G and K-type stars whose signal is at the same order of magnitude than the stellar noise. While the telescope-side AO system was installed on the ESO 3.6-m telescope in 2019, the infrared cryogenic spectrograph has been integrated at the telescope in early-2022 and has had first light in June 2022. Results from the first light mission show that NIRPS performs very nicely, that the AO system works up to magnitude I=14.5, that the transmission matches requirements and that the RV stability of 1 m/s is within reach While performance assessment is ongoing, NIRPS has demonstrated on-sky m/s-level stability over a night and <3 m/s level over two weeks. Limitations on the RV performances arise from modal noise that can be mitigated through better scrambling strategies. Better performances are also expected following a grating upgrade in July 2022; these will be tested in late-2022.

Ground-based and Airborne Instrumentation for Astronomy IX
Christopher J. Evans, Julia J. Bryant, Kentaro Motohara

Proceedings of the SPIE
Volume 12184
2022 August

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia