Absolute r-band magnitude versus redshift for galaxies in the HMCG compact group sample and in the CG₄ subsample. The colors are gray for all HMCG galaxies, red for CG₄ BGGs and blue for CG₄ satellites. The shaded gray region represents galaxies fainter than the SDSS flux limit (r>17.77). The dotted line denotes our doubly complete HMCG sample, while the thick dash-dotted lines shows the magnitude and redshift limits for the BGGs. The oblique line is three magnitudes above the SDSS flux limit and is our limit for BGGs in the first-step CG₄ selection process.