Upper panel: r′ − i′ vs. r′ diagram for galaxies with available spectroscopy. Red circles and blue crosses indicate cluster members and non members. The solid line gives the median color determined on member galaxies; the dashed lines are drawn at  ± 0.15 mag from this value. Lower panel: g′ − r′ vs. r′ diagram for galaxies with available spectroscopy. The dashed lines are drawn at  ± 0.3 mag from the median value determined on member galaxies.