Top: QFIT parameter as a function of the instrumental magnitude J for chip[1] of exposure HAWKI.2007-08-03T01:41:29.785.fits. In yellow, we highlighted two sources with anomalously high QFIT. The red line shows the saturation limit. Middle/bottom-left: location of the two sources (in yellow) on the image. Blue circles mark all stars for which we were able to measure a position and a flux. White pixels are those flagged according to the bad-pixel mask. We do not find stars too close to these bad pixels. Middle/bottom-right: the corresponding subtracted images. The first of the two high-QFIT stars (middle-right panel) we selected is in close proximity to a saturated star; it has been poorly measured and therefore has a large QFIT value. The second star (bottom-right panel) has a cosmic ray event close to its center, increasing its total apparent flux and shifting its center on the image. This star has been over-subtracted, resulting again in a larger QFIT value.