Example of a stack with six observations, targeting the star cluster NGC 2264. Upper panel: false-colour image in three energy bands 0.2 − 1.0, 1.0 − 2.0, and 2.0 − 12.0 keV to illustrate the different flux maxima of the detected objects. Lower panel: exposure map, giving the total exposure in ks, taking vignetting into account, with 4XMM-DR9s sources as red circles and 4XMM-DR9 sources as blue diamonds. The symbol size scales with the core radius of the extent model. Several low-quality (flagged) DR9 detections were not recovered in DR9s.