Notes. (1) QSO ID; (2) redshift; (3) reference for the redshift; (4) X-ray observation epoch; (5) telescope used for the X-ray observation; (6) observation ID; and (7) reference for the X-ray observation. We stress that we recomputed the fluxes as described in Appendix A. (8) Total exposure time of the observation epoch. Exposure times were filtered for background flaring and are reported separately for the EPIC PN, MOS1, and MOS2 cameras for XMM-Newton observations. (9) Time separations between epochs, in units of rest-frame days from the first observation epoch. We used the starting time of the observation, or the average of the starting times of the observations in the case of multiple pointings, as the time of one epoch. (10) Flux in the 0.5 − 7 keV band; and (11) X-ray variability factor, as defined in Sect. 3.1.

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