UVUDF: Ultraviolet Through Near-infrared Catalog and Photometric
  Redshifts of Galaxies in the Hubble Ultra Deep Field
  We present photometry and derived redshifts from up to eleven bandpasses for
9927 galaxies in the Hubble Ultra Deep field (UDF), covering an observed
wavelength range from the near-ultraviolet (NUV) to the near-infrared (NIR)
with Hubble Space Telescope observations. Our Wide Field Camera 3 (WFC3)/UV
F225W, F275W, and F336W image mosaics from the ultra-violet UDF (UVUDF) imaging
campaign are newly calibrated to correct for charge transfer inefficiency, and
use new dark calibrations to minimize background gradients and pattern noise.
Our NIR WFC3/IR image mosaics combine the imaging from the UDF09 and UDF12
campaigns with CANDELS data to provide NIR coverage for the entire UDF field of
view. We use aperture-matched point-spread function corrected photometry to
measure photometric redshifts in the UDF, sampling both the Lyman break and
Balmer break of galaxies at z~0.8-3.4, and one of the breaks over the rest of
the redshift range. Our comparison of these results with a compilation of
robust spectroscopic redshifts shows an improvement in the galaxy photometric
redshifts by a factor of two in scatter and a factor three in outlier fraction
over previous UDF catalogs. The inclusion of the new NUV data is responsible
for a factor of two decrease in the outlier fraction compared to redshifts
determined from only the optical and NIR data, and improves the scatter at
z<0.5 and at z>2. The panchromatic coverage of the UDF from the NUV through the
NIR yields robust photometric redshifts of the UDF, with the lowest outlier
fraction available.
