Top: Observed in-transit transmission spectrum in the Hα region for T1. The original data are shown in grey, while the smoothed version via a 9-point moving average is displayed in black. Middle: Modelled in-transit transmission spectrum for T1. Bottom: Residuals of the observed minus the model data. These results are displayed for all the in-transit data (left), as well as separately for the first (centre) and the second (right) halves of the transit.