The High-Redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey:
  The \spitzer Catalog
  We present 190 galaxy cluster candidates (most at high redshift) based on
galaxy overdensity measurements in the \spitzer/IRAC imaging of the fields
surrounding 646 bent, double-lobed radio sources drawn from the Clusters
Occupied by Bent Radio AGN (COBRA) Survey. The COBRA sources were chosen as
objects in the VLA FIRST survey that lack optical counterparts in the Sloan
Digital Sky Survey (SDSS) to a limit of $m_r=22$, making them likely to lie at
high redshift. This is confirmed by our observations: the redshift distribution
of COBRA sources with estimated redshifts peaks near $z=1$, and extends out to
$z\approx3$. Cluster candidates were identified by comparing our target fields
to a background field and searching for statistically significant
($\ge2\sigma$) excesses in the galaxy number counts surrounding the radio
sources; 190 fields satisfy the $\ge2\sigma$ limit. We find that 530 fields
(82.0\%) have a net positive excess of galaxies surrounding the radio source.
Many of the fields with positive excesses but below the $2\sigma$ cutoff are
likely to be galaxy groups. Forty-one COBRA sources are quasars with known
spectroscopic redshifts, which may be tracers of some of the most distant
clusters known.
