Three-sigma limiting magnitudes were determined by measuring the
RMS on each final stacked mosaic using the following expression:
where Z, X and k are the correspondent zero point, airmass and extinction coefficient respectively, is the PSF pixel area, and Texp is the exposure time. For the OACDF, the typical PSF FWHM is about 1'', which corresponds to a of 14 pixels. The three-sigma limiting magnitudes for the OACDF observations are summarised in Table 1. Note that the exposure time in the above equation is the one of the single dithering (column 4 in Table 1), whereas the RMS is the one measured in the stacked mosaic image.