Light curves displaying the R-band flux and combined R-, V- and g*-band PD and EVPA evolution. The inset shows a zoomed-in view of the ∼210° rotation seen in the optical data. The grey data points in the bottom panel show the evolution of the radio band (as shown in Fig. 1) for contrast. The vertical lines and hatched areas are as explained in Fig. 1 (see details in Sects. 3 and 4).