Transit light curve in the Ly-α line for Kepler-444 e+f (left panel) and Kepler-444 g (right panel). In the left panel, spectra in Visits A, B, C, and F have been averaged over common phase windows after being phased over Kepler-444 f ephemeris, and integrated in the range [−89; −37] km s^-1 (see first and second columns in Fig. A.3). In the right panel, spectra in Visit E have been integrated in the range [−103; −37] km s^-1 (see third column in Fig. A.3). In blue are plotted the theoretical transit light curves of the planets’ exospheres, subjected to a low photoionization and radiation pressure, and to interactions with the stellar wind. They were fitted independently to the data in the left and right panels.