Color–color diagram (J − H) versus (H − K_s) for the selected sample of SSCs (black dots). The theoretical stellar evolution track given by SB99 is shown for solar metallicity as the solid magenta line. The reddening vector corresponding to A_V = 1 is shown. The red stars are the sources detected in the control field, and the cross corresponds to the average color indices of the sample of 100 galaxies from the 2MASS survey, studied by Jarrett et al. (2003), with the length of the arms being equal to the standard deviations of those indices. The black cross represents the median errors of the cluster colors.