HAWK-I layout. The labels give the dimensions in arcsec and arcmin (and in pixels) of the four detectors and of the gaps. Numbers in square brackets label the chip denomination used in this work (note that the choice is different from that of Fig. 9 of Kissler-Patig et al. 2008). In each chip, we indicate the coordinate of the chip center. This is also the reference position that we used while computing the polynomial correction described in Sect. 5.1. The black asterisk in the middle shows the center of the field of view in a single exposure that we used in Fig. 2.