The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite, and the Two Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer (WISE) is mapping the whole sky following its launch on 2009 December 14. WISE began surveying the sky on 2010 January 14 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in 2010 November). WISE is achieving 5σ point source sensitivities better than 0.08, 0.11, 1, and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12, and 22 μm. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 61, 64, 65, and 120 at 3.4, 4.6, 12, and 22 μm, and the astrometric precision for high signal-to-noise sources is better than 015.

THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE