Comparison of VISTA and HAWK-I photometry in J band. The panel at the top shows the difference in photometric errors as a function of the apparent VISTA magnitude. Similarly, the bottom plot displays the difference in the measured source magnitudes. The histogram to the right shows the distribution of the magnitude difference as a kernel density. Assuming a Gaussian distribution, the differently shaded areas under the curve represent the 1, 2, and 3-σ limits.