Density plot of S/N vs. SExtractor’s SPREAD_MODEL for all detections. The dense vertical cloud located around SPREAD_MODEL is the point source (mostly stellar) locus. The fuzzy blob to the right of the stellar locus originates from galaxies and nebulosities, while the shallow cloud on the left is populated with cosmic ray hits and bad pixels. Note the asymmetry of the stellar locus caused by blended stars (most obvious at high S/N).