Finding chart for source X5 in the F390W WFC3 band covering an area of 2.4^′′ on each side. The cyan circle is centred on the X-ray position, indicated by a cyan cross, and it has a radius equal to the X-ray position uncertainty unc_X. The magenta circles denote the positions of the candidate counterparts. We mark in blue the candidate counterpart X5^c, which is the same as the one presented in Figs. 3 and 7.