Extragalactic survey using GALEX–spitzer matching fields

Abstract

We have used Spitzer observations of galaxies in the ELAIS-N1 region centered at 16h10m01s, +54◦30′36″ to extend the effective sensitivity of GALEX UV observations of the same region. Spitzer is more sensitive to external galaxies than GALEX and we have searched for UV sources at the positions of galaxies in the Spitzer catalog. This has allowed us to extend the sensitivity of the GALEX instrument to 27th magnitude. We have compared the derived number counts of galaxies in the two GALEX bands to standard models of galaxy evolution finding good agreement.The total contribution of these galaxies to the UV background is about 40 photons cm−2 sr−1 s−1 Å−1, in agreement with previous determinations.