The Buzzard Flock: Dark Energy Survey Synthetic Sky Catalogs
  We present a suite of 18 synthetic sky catalogs designed to support science
analysis of galaxies in the Dark Energy Survey Year 1 (DES Y1) data. For each
catalog, we use a computationally efficient empirical approach, ADDGALS, to
embed galaxies within light-cone outputs of three dark matter simulations that
resolve halos with masses above ~5x10^12 h^-1 m_sun at z <= 0.32 and 10^13 h^-1
m_sun at z~2. The embedding method is tuned to match the observed evolution of
galaxy counts at different luminosities as well as the spatial clustering of
the galaxy population. Galaxies are lensed by matter along the line of sight
--- including magnification, shear, and multiple images --- using CALCLENS, an
algorithm that calculates shear with 0.42 arcmin resolution at galaxy positions
in the full catalog. The catalogs presented here, each with the same LCDM
cosmology (denoted Buzzard), contain on average 820 million galaxies over an
area of 1120 square degrees with positions, magnitudes, shapes, photometric
errors, and photometric redshift estimates. We show that the weak-lensing shear
catalog, redMaGiC galaxy catalogs and redMaPPer cluster catalogs provide
plausible realizations of the same catalogs in the DES Y1 data by comparing
their magnitude, color and redshift distributions, angular clustering, and
mass-observable relations, making them useful for testing analyses that use
these samples. We make public the galaxy samples appropriate for the DES Y1
data, as well as the data vectors used for cosmology analyses on these
simulations.
