Figure 5.1: Sky map showing the 4XMM-DR13 distribution of XMM-Newton pointings in Hammer-Aitoff projection in Galactic coordinates, with red indicating new pointings with respect to the previous version of the catalogue, 4XMM-DR12 (blue). The galactic longitude ranges from 12 hours (left) to 12 hours (right), while the lower and upper poles are at -90 and +90 degrees in galactic latitude respectively.