Obtained significances (as defined in Sect. 3.1) for each target when analysed with respect to the optical (no hatch) and the X-ray (hatch) cluster centre, as well as when only using the i − z (yellow), the i − J (orange), and the z − J (red) colour of the sources. Transparency encodes the number of cluster member galaxies for which we find p_clm > 0.8: the more transparent, the fewer highly probable cluster member galaxies are found.