Power spectrum of XMM152737. The spectrum was obtained from two different observations. The main panel shows the power spectrum of the object obtained by XMM-Newton at 0.2−10 keV with 50 s time bins; these are over plotted together with an inset detailing the main peak. The dashed black line shows a Gaussian line fit to the main peak of observation number 0884991701. The black (Obs 1-0884991701) and red (Obs 2-0886210801) dashed lines in the main panel give the 95% significance level of both observations. The main period and its harmonics are indicated with the Ω symbol.