(r′− i′,r′) CMD of ID 617-A, associated with PSZ1 the source G183.26+12.25. The diagramconsiders extended sources within a region of 2.′5 × 2.′5 (1 × 1 Mpc) around the BCG of the system (represented by the large filled square in the plot). The solid line represents the fitted RS, which yields z_phot = 0.62. Dashed linescorrespond to the RS±0.15 locus, where likely cluster members are selected. An RGB image (composed using the g′, r′ and i′ frames) showing the 2.′5 × 2.′5 inner region of this cluster is superimposed on the plot.