Mount Graham International Observatory

Mount Graham International Observatory is an astronomical research facility located in the Pinaleño Mountains of southeastern Arizona at about 3,200 meters elevation. The site houses several major telescopes operated by scientists from around the world for studying distant objects in space.

The facility began operations in 1993 with two major instruments for astronomical research. A third large telescope was added years later, expanding the range of observations and research capabilities at the site.

The San Carlos Apache Tribal Council maintains opposition to the observatory's construction on their ancestral mountain, which holds religious importance for Western Apache peoples.

Access to the site is limited and visitors can join guided tours during warmer months, though advance arrangements are necessary. It's best to check conditions beforehand since availability and weather can affect when the location is accessible.

Scientists from multiple nations conduct research at the observatory, using instruments including the Large Binocular Telescope, which features two 8.4-meter mirrors.

Location: Graham County

Elevation above the sea: 3,191 m

Website: http://mgio.arizona.edu

GPS coordinates: 32.70122,-109.89206

Latest update: December 7, 2025 20:20