ULTRAVIOLET (2000 ANGSTROM) GALAXY COUNTS - COMPARISON WITH PREDICTIONS

A prediction of galaxy counts at 2000 Angstrom and m(2000) - B color d istributions is elaborated from published spectral energy distribution s and evolution models of galaxies. The comparison of the predictions to the observations at 2000 Angstrom is used to derive constraints on the local density of star-forming galaxies and their recent evolution. The data indicate a larger contribution of moderately blue ultraviole t-emitting galaxies than usually assumed in model counts at visible wa velengths. This discrepancy can reflect an underestimate of the local density of the actively star-forming galaxies, as well as an underesti mate of the spectrophotometric and maybe numeric evolution of these ob jects. Models which call upon a large contribution of very blue galaxi es to explain the well known number excess in galaxy counts near B = 1 8, produce blue tails in the m(2000) - B color distributions, which ar e not observed in the data.