Best-fitting Lyα models with applied constraints from ancillary observational data (Sect. 4.1). COS data and their errorbars are shown in black, the best-fitting model with the solid red line, the modelled intrinsic single-Gaussian Lyα profile with the dashed red line, and the observed SDSS Hβ scaled by Case B factor 23.5 with the dotted blue line. Parameters of the best-fitting model are shown in each panel.