Two-dimensional histograms for PCA selected sources from multiple exposures of the same sky region. The targets are the KN of GW170817 (top row; combining the first four exposures at CCD 36 in the g band) and the DES15C2eaz SN (bottom row; the first nine valid exposures at CCD 18 in the r band). We show the counts with no weight (first column), weighted by teff (second column), by PCA first component EVR (third column), and by first component quantile/rank (last column). In each diagram, a darker color corresponds to a higher count, and the red dot marks the (true) location of the target. Note that there is a possible variable star near the KN. For the SN, if there is only one source after the flag filtering, we set the EVR weight to be zero.