Previous
abstract 
Next
abstract
Latest results of an ongoing imaging and spectroscopic survey of faint galaxies in fields of Hubble Space Telescope spectroscopic target QSOs are presented. The primary results are that at moderate redshifts ($0.05 < z < 0.8$) most galaxies are surrounded by extended gaseous envelopes of $\approx 160 \ h^{-1}$ kpc radius and many or most Ly$\alpha$ absorption systems arise in galaxies. The dependence of the incidence and extent of these gaseous envelopes on galaxy type and environment is discussed, and the application of galaxy and absorption system pairs to measurements of galaxy dynamics on large spatial scales and to significant redshifts is described.
