THE LARGE-SCALE DISTRIBUTION OF LATE-TYPE GALAXIES BETWEEN VIRGO AND THE GREAT WALL

Neutral hydrogen data are presented for 88 of the Virgo Cluster Catalo g galaxies thought on morphological grounds to lie in the background o f the cluster. We confirm that the morphological assignment of cluster membership works quite well; very few of the ''background'' galaxies are in fact at cluster redshifts. The resulting sample of redshifts, a long with optical redshifts from the literature, allow us to explore t he large-scale distribution of galaxies in the space between the Local Supercluster and the Great Wall. Galaxies in a larger window around t he Virgo Cluster, but at redshifts between Virgo and the Great Wall, h ave a fairly low average number density, but the distribution is far f rom uniform: Some portions resemble voids, but in other portions galax ies can be assigned to clouds or filaments of appreciable size (someti mes containing bound groups). We investigate the luminosity function i n high- and low-density regions of our galaxy sample, which excludes t he Virgo Cluster proper. We find no significant difference. However, o ur selection procedures are insensitive to galaxies of very low surfac e brightness, which have been reported to be more abundant in low-dens ity regions. The average probability of a line of sight intersecting t he optical disk of our sample galaxies is derived separately for the V irgo Supercluster region (redshifts below 3500 km s-1) and for the reg ion behind (out to 10,000 km s-1). The number density ratio of Lyalpha forest lines to galaxies is larger by a factor of order 10 in the far (low-density) region than in the near. A survey of recent literature on galaxy redshifts uncovers a new candidate, MCG 0-32-16, for the low est redshift absorption line.