Light curve of each transit, computed by integrating the intensity of each spectrum in a spectral bin centered at the He triplet position for each observation. The horizontal axis shows the time from mid-transit in days, with the vertical dashed red lines showing contact points T1 (start of transit) and T4 (end of transit), and the dash-dotted red ones showing the contact points T2 (end of ingress) and T3 (beginning of egress). Error bars are shown in light gray and correspond to a 95% confidence interval.