7.2 Space Density of ``Cluster'' Centers

Allowing for galactic obscuration, some 50 to 60 cluster (or group or cloud) centers should lie within = 16.0 Mpc, or in a spherical volume of 17 x 10³ Mpc³. The average volume of space per cluster or ``cluster cell,'' then, is 300 Mpc<sup>3</sup>, and the average distance between adjacent ``cluster centers'' is on the order of 7 Mpc.

For comparison, the average diameter of the nearby groups, clouds, and clusters is about 2 Mpc; most condensations are well separated by regions of lower density.