DSS region (17′ × 20′) centered on A2933 (North is up and East is to the left). Galaxies identified as cluster members from spectroscopy are marked with different symbols corresponding to the three major peaks in the velocity histogram (purple squares: [26 000, 26 500] km s^-1, cyan diamonds: [26 500, 27 200] km s^-1, orange circles: [27 200, 28 500] km s^-1) which is plotted in Fig. 4. The isocontours corresponding to the galaxy density map with R < 19 are superimposed. The velocity histograms for the galaxies in the two circles (which have a 3.5 arcmin radius and are centered on the two subclusters) are displayed in Fig. 5.