Altitude profiles obtained with HARPS and method 3 for different positions across the umbra edge, given by parameter c in Eq. (10) and shown in Fig. 20. The vertical axis is the measured altitude, set to 23.8 km at at [4520–4540] Å for the profile calculated for c = 0. Other profiles are shifted vertically for clarity by steps of 40 km. The profiles in this figure are not built at HARPS native resolution, but at a smaller ≈0.6 Å/pixel resolution. The light-blue lines are 10 Å bins.