Panel A: CMD for 76 probable group members. Triangles represent the 23 most probable members with high-confidence spectroscopic redshifts in a narrow range [0.335, 0.365] centered on the group’s redshift (see panel B, shown as an inset of panel A). Galaxies are separated in blue and red according to color-determination scheme explained in Section 4.2.2. Panel C: 76 probable group galaxies’ bimodal distribution in color compared to the one of the large COSMOS-0.35 sample. Dot-dashed vertical lines indicate the inflection points of the two distributions.