Photometric precision of the J (left) and ﹩{W}^{{\prime} }﹩(right) bands. For each band, the upper panel shows ΔMAG versus MAG between pairs of two consecutive images, while the lower panel shows the photometric errors. The observed errors for three aperture sizes were calculated from the rms of ΔMAG in each 0.5 mag interval divided by ﹩\sqrt{2}﹩, while the theoretical errors were from SExtractor. In a 2 s exposure, the best photometric precision with a 6 pixels aperture reaches 8 mag; with a 3 pixels aperture, the limiting magnitudes in the J and ﹩{W}^{{\prime} }﹩ bands are 11.5 and 9.9, respectively.