Analysis of the overlap of the stellar and planetary sodium features for night one. Upper panel: all spectra in the stellar rest frame (SRF) taken during the transit in the wavelength range of the sodium doublet stacked on top of each other to create a 2D map. The black dashed line indicate the ingress and egress (here only ingress for for this partial transit). Middle panel: the sum over all spectra in the SRF, with a line profile fit as a dark blue dashed line. The FWHM is indicated as vertical, black dotted lines. Lower panel: spectra in the planetary rest frame (PRF), after division with the master-out spectrum. The position of the FWHM of the stellar sodium feature is indicated with dotted white lines. The low S/N residuals can be seen clearly as a strong trace in the lower panel.