Variability of observation 0112570101 of M 31’s central region. Computed with TW = 3 s (top left), 10 s (top right), 30 s (bottom left) and 100 s (bottom right). The colorbar is the same for all the plots and represents the variability divided by the detection level used for each time window, from less variable (𝒱/DL = 0.1, darker) to more variable (𝒱/DL = 1, lighter). The detected variable sources are marked by white circles. One of the sources that is detected with TW = 100 s, TW = 30 s and TW = 10 s in this observation was reported in Pietsch & Haberl (2005) as a type I X-ray burst, and is it marked here with white arrows.