Broad-band RM results. Top: the B-band ACF (dotted line) show a well defined centroid at zero lag (vertical blue line), while the B/r-band CCF shows the same peak at zero lag, a secondary peak at 3 days is also visible (vertical black line). In the same case as the B-band ACF, the r-band ACF (red line) show a peak at zero lag, however, one additionally faint peak is clearly visible between 10–20 days, in comparison with the ACF of the B-band. Bottom: the cross-correlation yields a centroid lag of 15.0 days (vertical black line). The red shaded area marks the range used to calculate the centroid.