SIMBAD references

We present our catalog of U, B, V, and I stellar photometry of the central 18 deg² area of the Small Magellanic Cloud. We combine our data with the Two Micron All Sky Survey and Deep Near-Infrared Southern Sky Survey (DENIS) catalogs to provide, when available, U through K_s data for stars. Internal and external astrometric and photometric tests using existing optical photometry (U, B, and V from Massey's bright star catalog; B, V, and I from the microlensing database of OGLE; and I from the near-infrared sky survey DENIS) are used to determine the observational uncertainties and identify systematic errors. We fit stellar atmosphere models to the optical data to check the consistency of the photometry for individual stars across the passbands and to estimate the line-of-sight extinction. Finally, we use the estimated line-of-sight extinctions to produce an extinction map across the Small Magellanic Cloud, and we investigate the nature of extinction as a function of stellar population.