Wyoming Infrared Observatory, Astronomical observatory on Jelm Mountain, Wyoming, US

Wyoming Infrared Observatory is a research facility on Jelm Mountain with a 2.3-meter telescope positioned at about 9,656 feet elevation. The site was chosen for its dark skies and dry air, which create ideal conditions for observing infrared radiation from space.

The facility began operations in September 1977 with support from the Wyoming State Legislature and the National Science Foundation. In its early years, it housed the world's largest working infrared telescope and led to major discoveries in infrared astronomy.

The observatory's name is often shortened to WIRO, and its work is tied to the University of Wyoming in Laramie. Its 2.3 m mirror was built comparatively thin, which kept construction costs low. Researchers there have searched for runaway stars, monitored short-term variations in blazars, and tracked massive binary stars.

The observatory sits on the summit of Jelm Mountain at 2,948 m, 40 km southwest of Laramie, reached by a mountain road; access can be restricted by weather. Arrangements for a visit go through the University of Wyoming and must be planned in advance, for groups or individuals. Visitors follow the observatory's safety rules during their stay.

The 2.3 m primary mirror was made comparatively thin, which kept construction costs low. The secondary mirror can be wobbled under computer control to sample adjacent sky areas in quick succession. In 1979, soon after first light, the first dust-formation episode of a Wolf-Rayet star was recorded on UY Scuti.