Flat-field data (delta flat) in the r-band obtained by averaging the science observations that were already flat-fielded using the standard ASTROWISE pipeline. The values shown in the colorbars represent the (dimensionless) relative change with respect to the original flatfield. The top panel shows the full mosaic. The bottom figures show the bottom-left chip with a zoom-in of the top-left corner of that chip (red square). Some structure is visible, likely due to variations in the illumination, as well as some low-level fringing.