Comparison of X-ray detection ellipses in three 40″ × 40″ closeups, centered at the coordinates that are printed in blue, of the 2009 (left) and 2016 (right) Chandra/ACIS fields, using binning factors of 1 (green), 2 (yellow), and 4 (purple) pixels. Ellipses that were selected for the final source list are drawn with solid lines. The background images are 2-pixel binned. Upper panels: portion of the [DB2001] Cl05 cluster, middle panels: region near the edge of the 2016 field, and lower panels: region near the 2009 edge.