Deep UV photometry of galaxies & the extragalactic UV background

We have performed multifiber spectroscopy of UV-selected galaxies obtained by the balloon-borne FOCA telescope. 55 galaxies were found in 0.25 square degrees. The number-magnitude, redshift, and color distributions show that strong evolution is occurring in the UV-selected population. A mildly luminosity-dependent model normalized to the star formation history derived from optical surveys is a good fit to the distribution. Keck spectroscopy reveals that galaxies in the high-redshift tail are both dwarfs and giants, including “giant starburst” galaxies. One third of these high-redshift galaxies have companions inside 100 kpc consistent with being dynamically bound. The results are consistent with current limits on the extragalactic UV background.