Surveying the Agents of Galaxy Evolution in the Tidally-Stripped, Low
  Metallicity Small Magellanic Cloud (SAGE-SMC). I. Overview
  The Small Magellanic Cloud (SMC) provides a unique laboratory for the study
of the lifecycle of dust given its low metallicity (~1/5 solar) and relative
proximity (~60 kpc). This motivated the SAGE-SMC (Surveying the Agents of
Galaxy Evolution in the Tidally-Stripped, Low Metallicity Small Magellanic
Cloud) Spitzer Legacy program with the specific goals of studying the amount
and type of dust in the present interstellar medium, the sources of dust in the
winds of evolved stars, and how much dust is consumed in star formation. This
program mapped the full SMC (30 sq. deg.) including the Body, Wing, and Tail in
7 bands from 3.6 to 160 micron using the IRAC and MIPS instruments on the
Spitzer Space Telescope. The data were reduced, mosaicked, and the point
sources measured using customized routines specific for large surveys. We have
made the resulting mosaics and point source catalogs available to the
community. The infrared colors of the SMC are compared to those of other nearby
galaxies and the 8 micron/24 micron ratio is somewhat lower and the 70
micron/160 micron ratio is somewhat higher than the average. The global
infrared spectral energy distribution shows that the SMC has ~3X lower aromatic
emission/PAH (polycyclic aromatic hydrocarbon) abundances compared to most
nearby galaxies. Infrared color-magnitude diagrams are given illustrating the
distribution of different asymptotic giant branch stars and the locations of
young stellar objects. Finally, the average spectral energy distribution (SED)
of HII/star formation regions is compared to the equivalent Large Magellanic
Cloud average HII/star formation region SED. These preliminary results are
expanded in detail in companion papers.
