Color composite image of SDSS CG 6

Color composite image of SDSS CG 6. The field of view is 5.15 arcminutes² (1.12 megaparsecs across at the distance of the group). The squares are galaxy members of the group. The circles are galaxies in the foreground and background of the group. The inner circle is the smallest circle that contains the centers of the group members with magnitudes within 3 magnitudes of the brightest group member. The outer concentric circle corresponds to the angular diameter that contains no other (external) galaxies within 3 magnitudes of the brightest group member, as defined by Lee et al. (2004). The inset (inner 0.2 h1 Mpc) shows the four central galaxies in the group that would merge into one and form a galaxy with magnitude M_r~-23.4, typical for the brightest galaxies of fossil groups.