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The SPIRou wavelength calibration for precise radial velocities in the near infrared

Abstract : Aims. SPIRou is a near-infrared (nIR) spectropolarimeter at the CFHT, covering the YJHK nIR spectral bands (980−2350 nm). We describe the development and current status of the SPIRou wavelength calibration in order to obtain precise radial velocities (RVs) in the nIR.Methods. We make use of a UNe hollow-cathode lamp and a Fabry-Pérot étalon to calibrate the pixel-wavelength correspondence for SPIRou. Different methods are developed for identifying the hollow-cathode lines, for calibrating the wavelength dependence of the Fabry-Pérot cavity width, and for combining the two calibrators.Results. The hollow-cathode spectra alone do not provide a sufficiently accurate wavelength solution to meet the design requirements of an internal error of < 0.45 m s−1, for an overall RV precision of 1 m s−1. However, the combination with the Fabry-Pérot spectra allows for significant improvements, leading to an internal error of ∼0.15 m s−1. We examine the inter-night stability, intra-night stability, and impact on the stellar RVs of the wavelength solution.
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Submitted on : Friday, April 9, 2021 - 10:16:01 PM
Last modification on : Wednesday, April 14, 2021 - 3:21:01 AM


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M. J. Hobson, F. Bouchy, N. J. Cook, E. Artigau, C. Moutou, et al.. The SPIRou wavelength calibration for precise radial velocities in the near infrared. Astronomy and Astrophysics - A&A, EDP Sciences, 2021, 648, pp.A48. ⟨10.1051/0004-6361/202038413⟩. ⟨hal-03194932⟩



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