Filtering of Cen X-3 light curves using a log-normal distribution of counts in the 3–70 keV band (see Sect. 3.3). Left panel: light curve since the beginning of observation on 2015 November 30. The pink vertical bands indicate the excluded periods; the horizontal lines indicate the rate limits. Right panel: histogram of counts in logarithmic scale with horizontal lines indicating the adopted limits. We considered as good time intervals those encompassing the ±5σ deviations from the central peak value.