Wide-field Infrared Survey Explorer

Wide-field Infrared Survey Explorer (WISE) is a NASA Medium-class Explorer Program (MIDEX) satellite launched in December 2009, aimed at a 1 year mission to image the whole sky in infrared, in order to observe stellar nurseries and detect asteroids. A reason for such an infrared mission is that infrared penetrates dust, thus observing YSOs otherwise hidden. It surveyed four wavelengths in the infrared:

Differences in these, e.g., w1-w2 and w2-w3 are useful in identifying obscured active galactic nuclei (AGNs).

When the intended mission was completed, the spacecraft was put in hibernation even though it was still operational. It was revived in 2013 for a new mission, NEOWISE (for Near Earth Object WISE), specifically to search for near-Earth objects (NEOs), and is still active as of 3/2024. Infrared has an advantage over ground visible-light observations in estimating the size of observed NEOs: thermal emission is a greater contributor to such an object's infrared magnitude, which has more relationship to the object's size and less to its albedo than do visible-light magnitudes.

"WISE" is used as a designator for WISE discoveries, but so are numerous variants (such as "WISEA") for various discoveries and astronomical catalogs, some of which are listed here.