Data reduction (pipelines and analysis software) is a critical and necessary component required to go from observations to scientific results. With the maturation of near-infrared high-resolution spectroscopy, especially when used for precision radial velocity, data reduction has been faced with unprecedented challenges in terms of how one goes from raw data to clean, calibrated, extracted, and corrected data with required precision of thousandths of a pixel. Here we present APERO and LBL. APERO is a pipeline designed to reduce observations, specifically focused on our first instrument, SPIRou, the near-infrared spectropolarimeter on the Canadian France Hawaii Telescope. The line-by-line (LBL) method of pRV measurements is designed to be outlier-resistant while taking advantage of the full RV content of the input spectra. The method splits high-resolution spectra into thousands of absorption lines for which it measures individual velocities. These velocities are combined through a simple finite mixture model that accounts for the likelihood that a given line may be an outlier due to telluric absorption or other observational biases. The combination of APERO and LBL with SPIRou leads to m/s precisions in radial velocity.

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Paper accepted by PASP. https://arxiv.org/abs/2211.01358