The Arizona CDFS Environment Survey (ACES): A Magellan/IMACS
  Spectroscopic Survey of the Chandra Deep Field South
  We present the Arizona CDFS Environment Survey (ACES), a recently-completed
spectroscopic redshift survey of the Chandra Deep Field South (CDFS) conducted
using IMACS on the Magellan-Baade telescope. In total, the survey targeted 7277
unique sources down to a limiting magnitude of R = 24.1, yielding 5080 secure
redshifts across the ~30' x 30' extended CDFS region. The ACES dataset delivers
a significant increase to both the spatial coverage and the sampling density of
the spectroscopic observations in the field. Combined with
previously-published, spectroscopic redshifts, ACES now creates a
highly-complete survey of the galaxy population at R < 23, enabling the local
galaxy density (or environment) on relatively small scales (~1 Mpc) to be
measured at z < 1 in one of the most heavily-studied and data-rich fields in
the sky. Here, we describe the motivation, design, and implementation of the
survey and present a preliminary redshift and environment catalog. In addition,
we utilize the ACES spectroscopic redshift catalog to assess the quality of
photometric redshifts from both the COMBO-17 and MUSYC imaging surveys of the
CDFS.
