(J − H) vs. (H − K_s) color-color diagram and K_S vs. (H − K_S) color-magnitude diagram for the observed sources. The black symbols correspond to the sources that are probably cluster members (see Sect. 5.1), and the gray symbols correspond to the remaining sources in the field of view (contaminants). The solid lines in both diagrams represent the adopted models for an age of 1 Myr and a distance of 1.5 kpc. The arrows show the displacement caused by an extinction of 1 mag in K_S according to the assumed extinction law (see Sect. 2.1). The dashed lines show the limits of the reddening band in the color-color diagram, defined by the reddening vector and the extreme ends of the model isochrones in color.