Some representative examples of the calculated PDSs (small vertical lines as errors of the mean) with corresponding fits (red lines) in f × p as y-axis units. Two different cases are shown: transitions from the high to low state (left panels) and vice versa (right panels). The (middle) time locations of the PDSs are marked as red arrows in the lower panel of Fig. 1. All displayed fits are directly compared in the bottom panels (both panels comprise days 310–320 and 350–360 for comparison).