Stellar wind parameters as obtained from the fit of the time-resolved colour-colour diagrams of observation 201, plotted as a function of the orbital phase (see also Table 1). The parameters are: the covering factor, f_c (upper panel), the mean column density, ${\overline{N}}_{\mathrm{H},\mathrm{w}}$ (middle panel), and the scatter in column density parameter, δN_H, w (lower panel). The shaded areas represent the 68% confidence contours. The yellow curves are the neutral column density profiles produced by the smooth wind model (El Mellah et al. 2020) at high (solid) and low (dashed) stellar mass loss rates.