WFI R-band image of the A2440 field (12′ × 14′). Galaxies identified as cluster members from spectroscopy (Flag 0 and 1) are marked with different symbols according to the velocity range (purple squares: [24 000, 27 600] km s^-1; orange circles [27 600, 30 000] km s^-1). The isocontours of red sequence galaxy density maps with magnitude limit R < 19 are superimposed. The velocity histograms of the three regions with 2.5 arcmin radius delimited by circles (corresponding to the three subclusters A2440A, A2440B, and A2440C) are displayed in Fig. 13. North is up and East is to the left.