Figure 5.1: Hammer-Aitoff equal area projection in Galactic coordinates of the 5XMM-DR15 fields. The colours represent the density of the observations, with yellow the lowest density to deep blue, the highest density.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.