The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance

TL;DR

The paper introduces the Wide-field Infrared Survey Explorer (WISE), a space-based all-sky mid-infrared survey designed to surpass prior surveys in sensitivity and coverage. It details the mission design, four-band infrared instrument, spacecraft, operations, and IPAC/IRSA data processing pipelines, along with early on-orbit performance. Key results include 5σ point-source sensitivities of 0.08–6 mJy across W1–W4, astrometric precision better than 0.15 arcsec for bright sources, and near-complete sky coverage achieved within six months, followed by a planned data-release program. The work outlines a broad scientific program spanning brown dwarfs, ULIRGs/AGN, asteroids, and Galactic/extragalactic structure, and discusses data products and follow-up opportunities, establishing WISE as a foundational resource for decades of infrared astronomy.

Abstract

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 2 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 is mapping the whole sky following its launch on 14 December 2009. WISE began surveying the sky on 14 Jan 2010 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 November 2010). WISE is achieving 5 sigma 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 microns. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.1, 6.4, 6.5 and 12.0 arc-seconds at 3.4, 4.6, 12 and 22 microns, and the astrometric precision for high SNR sources is better than 0.15 arc-seconds.

Figures (19)

• Figure 1: Diagram showing the WISE flight system in survey configuration with cover off. The spacecraft bus to the left of the bipod supports was provided by BATC, and the cryogenic instrument to the right of the bipods was provided by SDL.
• Figure 2: Coverage by WISE in one frame (every 11 seconds), in one orbit, in two orbits, and in many orbits. The gray levels show the depth of coverage with the darker areas having more coverage..
• Figure 3: Cartoon showing WISE coverage on the sphere for 1 orbit, for 2 consecutive orbits, and for 2 orbits separated by 20 days, illustrating the highly redundant coverage at the ecliptic poles.
• Figure 4: WISE pointing and orbit during the June solstice. Note that WISE points perpendicular to the Earth-Sun line and not toward the zenith.
• Figure 5: WISE survey coverage vs. date. As of 15 July 2010 more than 99% of the sky had been covered to depth of 8 frames or more. The fraction of the sky covered to a depth of 4, 12 or 16 frames is also shown. The dotted portions of the curves show the anticipated coverage until the expected exhaustion of the cryogen. The vertical dashed line shows when the 22 $\mu$m channel saturated after the actual exhaustion of the secondary tank. The small slowdowns in the survey progress occur when the Moon crosses the scan path. The dashed line shows a simple prediction of the sky coverage based only on the longitude of the Sun, starting on 14 Jan 2010.