Precise RVs and Stellar Magnetic Field Measurements via LSD

To improve the accuracy of planetary mass estimates and ultimately detect Earth twins, it is crucial to find more reliable radial velocity extraction methods.
The Least-Squares Deconvolution (LSD) technique has been used to infer the stellar magnetic flux from spectropolarimetric data for the past two decades. It relies on the assumption that stellar absorption lines are similar in shape and only scale up by a wavelength-specific factor. Although this assumption is simplistic, LSD provides a good model for intensity spectra and likewise an estimate for their Doppler shift.
We present a radial velocity extraction pipeline combining LSD with state-of-the-art preprocessing techniques. The flexibility of LSD allows to select or exclude spectral lines or pixels at will, providing a means to exclude variable lines or pixels affected by instrumental problems. The LSD pipeline was tested on HARPS-N data for which it delivered RV time series with on average 10 per cent lower scatter as compared to the HARPS-N RV extraction pipeline based on the Cross-Correlation Function technique. The full description of this pipeline will be provided in an upcoming paper: Lienhard et al. (soon to be submitted).