Steps applied to the observations before the cross-correlation analysis. As an example, we show the data of the first night. Top panel: original time series. Middle panel: time series obtained after correcting trie telluric contamination and normalising all spectra to the same continuum level as presented in Merritt et al. (2020). Bottom panel: time series of spectra after masking the columns of pixels affected by telluric residuals and the region below 4000 Å due to a lower S/N