Average Stokes parameters of Cyg X-1 obtained during season 2 in the R band. The color coding and size of the circle correspond to the orbital phase and 1σ uncertainty, respectively. The solid blue curve corresponds to the best fit with the Fourier series given by Eq. (2). The dashed orange line corresponds to the to the best-fit model of a scattering cloud on an eccentric orbit from the appendix of Kravtsov et al. (2020).