Orbital profiles of the polarization and flux of Cyg X-1 in the optical band. Top panel: intrinsic polarization of Cyg X-1 in the R filter, folded with the orbital period (seasons 1–3 are plotted). Each circle with the 1σ error bar shows the average polarization, calculated within a 30-min bin. Bottom panel: TESS magnitude of Cyg X-1, folded with the orbital period. Different colors (from cold to warm) correspond to different orbital periods T1–T11. The solid black line shows the average orbital profile.