Panel A: integral source flux (E > 1 TeV) vs. source size scatter plot with colors representing the different classes of firmly identified sources. For HGPS sources modeled as single Gaussians, the size is its width (σ). For sources modeled as multiple Gaussians (indicated with a circle around the marker), the size is the RMS of the two-dimensional intensity distribution (see Eq. (16)). For sources with shell-like morphology (SNRs), the size is the outer shell radius. To improve the visibility of the plot, we do not show the SNR Vela Junior (HESS J0852−463) at a size of 1° and a flux of 103% Crab. We illustrate the approximate sensitivity limit of the HGPS, as defined in Eq. (28), with an assumed point-source sensitivity of 1% Crab and an uncertainty band with a factor ±2 to represent the sensitivity variations in the survey region (see caveats in main text). Panel B: distribution of the integral fluxes (E > 1 TeV)of the HGPS sources; colors are shown as in panel A. Panel C: distribution of the HGPS source sizes; colors shown as in panel A. The first bin contains 30 sources, of which 17 are compatible with point-like sources according to Eq. (18). As in panel A, we omit Vela Junior, at a size of 1°.