Left: colour–colour diagram of i − H_E versus g − H_E for all sources in the full SourceExtractor catalogue. The points represent the objects with I_E ≤ 22.96 identified as galaxies in Fig. 20 with z_phot ≲ 0.1 (green dots), and optically identified (red dots) or spectroscopically confirmed (magenta dots) cluster members (z_spec ≲ 0.03). Filled dots are for galaxies with uncertainty in the colour larger than 0.1 mag. The black dashed line shows the bisector fit to the data, (i − H_E) = (0.99 ± 0.02) × (g − H_E) − (1.06 ± 0.01), σ = 0.26, for galaxies with a colour uncertainty σ_col ≲ 0.1, while the solid lines delimit the region within the 3 σ dispersion of the relation, where 99.7% of the spectroscopically and visually identified members are located. The black solid horizontal line shows the upper limit in colour observed in the spectroscopically confirmed cluster members (i − H_E < 1.1). Right: colour–magnitude relation of i − H_E versus I_E for the same sample of galaxies but limited to those objects identified as potential cluster members in the i − H_E versus g − H_E colour–colour diagram (left panel). Galaxies are identified using the same symbols, with the exception of green dots within black circles, which are systems lying > 3 σ from the mean colour–magnitude relation, where 99.7% of the spectroscopically and visually identified cluster members are located. Those located below the colour–magnitude relation are possible star-forming cluster members.