Galaxy detection. Left: detections from an extended-source detector, sorted by the difference in detection strength between the “yellow galaxy” and “yellow point-source” detectors. The bright stars are likely included because their saturated cores cause difficulty in correctly measuring the signal-to-noise ratio. The remaining sources are all galaxies, except for one fast-moving asteroid that is spatially extended. Right: relative strength of detection of sources in the extended vs. PSF detection filters. The extended-source filter used here is a 1″ FWHM round Gaussian. There is a clear line of sources with a detection ratio around 0.95, corresponding to point sources. Sources with ratios above unity are closer in profile to the target profile than to a point source, with the largest ratios probably corresponding to sources that are approximately equal to the target profile.