  We present the Spitzer IRAC/MUSYC Public Legacy Survey in the Extended
CDF-South (SIMPLE), which consists of deep IRAC observations covering the
~1,600 arcmin^2 area surrounding GOODS-S. The limiting magnitudes of the SIMPLE
IRAC mosaics typically are 23.8, 23.6, 21.9, and 21.7, at 3.6 um, 4.5 um, 5.8
um, and 8.0 um, respectively (5-sigma total point source magnitudes in AB). The
SIMPLE IRAC images are combined with the 10'x15' GOODS IRAC mosaics in the
center. We give detailed descriptions of the observations, data reduction, and
properties of the final images, as well as the detection and photometry methods
used to build a catalog. Using published optical and near-infrared data from
the Multiwavelength Survey by Yale-Chile (MUSYC), we construct an IRAC-selected
catalog, containing photometry in UBVRIz'JHK, [3.6 um], [4.5 um], [5.8 um], and
[8.0 um]. The catalog contains 43,782 sources with S/N > 5 at 3.6 um, 19,993 of
which have 13-band photometry. We compare this catalog to the publicly
available MUSYC and FIREWORKS catalogs and discuss the differences. Using a
high signal-to-noise sub-sample of 3,391 sources with ([3.6] + [4.5])/2 < 21.2,
we investigate the star formation rate history of massive galaxies out to z ~
1.8. We find that at z ~ 1.8 at least 30% +/-7% of the most massive galaxies
(Mstar > 10^11 Msol) are passively evolving, in agreement with earlier results
from surveys covering less area.
