Distribution of eruption dates (in days of the year) over time, based on Table 1, for the optical detections only (panel a)) and for all detections (panel b)). The red line is the best fit to the optical data (in black). The grey area is the corresponding 95% confidence region. In panel b) the blue open circles are the optical peak dates corresponding to the X-ray detections (see the text). The blue filled circles are the same dates shifted by 175 d. The blue solid line is the best fit to all solid data points and the blue dashed lines mark its 95% confidence region.