Non-uniform exposure time over the field of view of El Anzuelo due to the combination of dithered exposures and masking of cosmic rays. Top row. example exposure maps for filters F200W and F444W. White isophotes indicate the position of the arcs and deflectors with respect to features in the exposure map. Bottom row. diagonal of the data covariance matrix (i.e., the noise map) estimated from the exposure map and the model-predicted flux to compute the shot noise contribution. The detector edge and cosmic ray imprints are still clearly visible in the noise map and are taken into account during modeling.