Light curves of each of the four XMM–Newton/OM photometric filters: U (panel A), UVW1 (panel B), UVM2 (panel C), UVW2 (panel D); and light curves, averaged over each observation, of XMM–Newton/pn in the bands 0.5–2 keV (panel E) and 2–10 keV (panel F). The U and UVW1 filters were not available during Obs. 5. The blue solid lines represent the mean value of the count rate over the five observations, while the blue dashed lines represent the standard deviation (i.e. the root mean square of the deviations from the mean).