PSF surface-brightness profiles versus the radius r for a 0 mag point source. Individual PSFs are drawn with coloured lines and symbols as indicated in the figure, see also Table 1. PSFs of stacked SDSS images are shown in the upper part of the figure, as a function of 10³ × r; PSF_V,0m, PSF_i,0m, and the outer regions of PSF_K71 are shown in both parts as references. Extrapolated PSFs are shown with dotted lines. The light (medium) grey region indicates the PSF core (blue sky) and the white region the aureole, as defined for PSF_CV,1 and PSF_CV,2 (CV83).