Left: database sources included in tile AIS_480 are shown as purple dots. They result from merging two visits (right); the large black dots are sources within 0.°5 from the center of the coadd, thus in principle meeting the criterion for our catalog (and BCScat). The smaller black dots are sources in nearby fields. Right: over the pipeline-merged sources with fov_radius < 0.°5 (black dots), the visit-level sources are shown in dark yellow (visit with NUV exposure only) and green (visit with both NUV and FUV exposures). On the latter, blue circles mark sources with significant detection also in FUV. We use large/small symbols to indicate sources inside/outside of a 0.°5 radius from the actual center of each visit. In the database coadd all purple sources are given exposure times equal to the sum of the two visits, but this is correct only for those in the small intersection of yellow and green dots. Also, sources from the rim of both visits appear to have a small distance from the coadd center, because the pipeline assigned a value of fov_radius based on the coadd center, rather than on the center of the parent observation, and therefore these rim sources will not be discarded by a selection in fov_radius.