1995A&AS..109..511R

We report the results of a preliminary survey for low surface brightness galaxies (LSBG's) in the field, visually selected from film copies of SERC J Schmidt plates. Spectroscopy and photometry indicate that the resulting sample consists of dwarf galaxies. These galaxies of low surface brightness are also of low total luminosity, as found in the Virgo and Fornax galaxy clusters. The population sampled by this survey extends to redshifts of z≃0.05 and has a number density of n≃(8±5)x10^–3h³/Mpc³. This is about 6±4% of the number density for normal galaxies in the corresponding magnitude range of -14≥M_B≥-20 represented in a standard (Efstathiou et al. 1988) luminosity function. About half of the population is already represented in the general galaxy luminosity function, making the new contribution of our population fairly small. This density is too low to explain the excess of galaxies observed at B>24 (e.g., Tyson & Seitzer 1988), though magnitudes and diameters of our galaxies are consistent with those of the excess galaxies. We conclude that on the basis of its space number density, the population we have surveyed does not contribute significantly to the general galaxy luminosity function and so is not a candidate for explaining the excess of faint galaxies.