Mean number of significant detected galaxy concentrations (SDGC) around the sample of 491 clusters in W1 from T0006+Th09 as a function of cluster detection level (S/N) in the T0006 sample, in regions of different radii. From top to bottom the radii are: R < 1 Mpc, R < 2.5 Mpc, 1.5 < R < 3.5 Mpc, and 2.5 < R < 5 Mpc. Filled circles: SDGC detected with galaxies in the largest possible magnitude interval (see text). Open stars: SDGC detected with galaxies brighter than the considered cluster cDs (see text). Continuous line: mean number of SDGC in the random sample with its error (dotted lines). The uncertainty (interval between the two dotted lines) is computed as the second-order momentum of the SDGC distribution across the field of view (in pixels of 0.2  × 0.2 deg²). By “all galaxies” and “bright galaxies” we mean galaxies belonging to intervals I and II, respectively.