Projection Effects in the Abell Catalogue
  We investigate the influence that projection effects have on the completeness of the the Abell cluster catalogue in the context of an $\Omega_0$=1 CDM Universe. We construct a galaxy catalogue and identify clusters using an algorithm that mimics Abell's method. Over 30% of Richness Class $\geq$1 clusters have been selected despite not meeting the required intrinsic (3D) richness criterion. Velocity dispersions are shown to have been systematically overestimated. 
M. P. van Haarlem (University of Durham)