Variability on kilosecond time scales detected during the 2009 Long Look observation. Left panel: rms variability computed for the pn observation over the 0.2−10 keV band; arrows mark upper limits, error bars are at 1σ confidence level. Middle panel: 0.2 − 1.5 and 1.5−10 keV background-subtracted pn light curves binned to 2 ks; the numbers in the 1.5 − 10 keV light curve mark the eight time intervals on which time-resolved spectral analysis was performed. Right panel: three representative spectra extracted during the 2nd, the 7th, and the 8th time intervals of the 2009 Long Look observation.