Summary of residual distributions for a single 20 s exposure (top) and for 20×20 s coadded exposures (bottom). The top-left panel shows the overall distribution of the residuals, with the best-fit standard deviation assuming a Gaussian shape. The top right panel shows the 24 transmissions of each sub-image of a single image, fitted independently. The middle panels show the residuals (for all sub-images) as a function of the instrumental coordinates of the camera sensor. The bottom panels show the residuals as a function of the Gaia color (left) and the Gaia G magnitude (right), respectively.