Integrated flux F_Int as a function of its uncertainty ΔF_Int for all Hi-GAL bands as indicated. The black points are all the sources in each band catalogue; the ten cyan contours (equally spaced in source density) indicate the source density in the most crowded area. The green points are the subset of sources that possess a counterpart in at least two adjacent bands (so as to form an SED with at least three photometric points, see Elia et al., in prep.). The blue line represents S/N_Int = 3.