Doppler shifts versus exoplanet phase for the NaD|$_2$| line. Blue indicates ingress, red indicates mid-transit, and green indicates the egress part of the transit. Evidently, the largest residual peak is indeed blueshifted as described in the text. At egress, there is a significant redshift (Fig. A3 shows the stacked residual spectra for all the exposures). A constant y-offset is applied for visibility purposes. We note that the Rossiter–Mclaughlin effect cannot generate signals larger than 100 ppm (Wyttenbach et al. 2017).