An important compilation of galaxies in the Virgo cluster was presented by
Binggeli, Sandage and Tammann
1985, Astron. J. 90, 1681. Their Virgo Cluster Catalog (VCC) consists of 2096 galaxies which they believed,
based on examination of high quality photographic plates, are likely cluster members.
Note that their investigation of the cluster
was based on many fewer redshifts than are available today.
To the right is the sky distribution of possible cluster
members as appeared in their paper.
Using the Virgo AGC/α.40 data files (linked above), plot (on the same graph)
the sky distribution of galaxies in the (a)
optical sample and (b) the α.40 galaxies. Assign red symbols to the optical sample
and blue ones to the α.40 galaxies. Keep in mind that the α.40 sample is limited
to the Dec = +15 deg strip of grids so it stops at +16 degrees.
From Figure 2 of
Binggeli, Sandage & Tammann 1985