Left: dots showing all galaxies identified in the region from SDSS, with the corresponding galaxy density shown by filled contours. Red crosses denote the centre of mass of the sub-clusters identified by Dahle et al. (2002). Right: SDSS composite image from bands g, r, i within the area shown by the white square in the left plot. The two brightest galaxies are labelled, where BCG-A (13:06:49.99, +46:33:33.35) has a redshift of 0.232, and and BCG-B (13:06:45.69, +46:33:30.74) has a redshift of 0.218. The width of the dashed circles around galaxies with photometric redshifts is proportional to the error on the measurement, where they start at 4% and get thinner as the error increases. The maximum photometric error is 50%.