Left: FORS2 spectra of the three confirmed cluster members, smoothed with a 7 pixel boxcar filter. In the first panel we overlay the telluric absorption spectrum in red. Sky emission lines are shown in red in the bottom panel. The inset shows the FeII and MgII lines. Right: I − H colour − magnitude diagram of XMMUJ0044. Only objects within 1′ radial distance from the cluster X-ray center are shown. The three confirmed members are shown in blue circles and the interlopers are marked in green. The ID numbers refer to Table 1. The large, central galaxy is identified by a magenta star. We also flag the red (3.7 < I − H < 4.6) galaxies that are likely associated with the cluster (red triangles). The horizontal dashed lines refer to SSP model galaxies with different stellar formation epochs at the cluster redshift (red line: z_f = 5, blue line: z_f = 3). The solid blue line refers to the de-evolved CMD of XMMUJ2235 at z = 1.58. The 50% completeness limit in the H-band is shown by a vertical dashed line.