Color distribution of galaxies within r_200,wl (red histogram) and in a control area (normalized to the cluster solid angle, blue histogram) for O32. The vertical lines indicate the expected color range of the red sequence. The peak on the right corresponds to the color expected for the cluster redshift, while the second peak represents a contaminating structure along the line of sight spectroscopically confirmed at z = 0.136 (see text for details). For O32, the color range was reduced by 0.1 mag on the blue side to exclude this contamination. Only galaxies brighter than M_V^e = −20 mag, assuming all galaxies are at the O32 redshift, are considered, which boosts the low redshift contamination.