(H× [H–K_s]) CM diagram for all stars detected by GeMS/GSAOI. The solid line shows the statistical separation between cluster members (black points) and contaminating field stars (gray dots), as derived from Santos et al. (2012). The dotted line is an extrapolation of the solid line at faint magnitudes. Red triangles are stars from the control field. Stars flagged with red open squares are potential NIR excess stars (see Sect. 5.2). Stars flagged with violet open squares are stars detected in both H and K_s, but not in J. Stars flagged with blue open squares are also detected only in H and K_s, but they are likely to be field stars.