Large Binocular Telescope

The Large Binocular Telescope is a double optical telescope on Mount Graham in Arizona with two primary mirrors that each measure 8.4 meters (27.6 feet) across. Both mirrors sit on a shared moving mount at an elevation of 3221 meters (10567 feet) above sea level.

Work on this telescope first started in 1996 and the project reached completion in 2004 after several legal disputes with environmental groups and indigenous communities were resolved. The choice of Mount Graham as a site went through many approval processes and public debates.

Some members of the San Carlos Apache Tribe still connect this mountain to spiritual practices from their ancestors. The location led to conversations about access to sacred places and scientific research in an area with cultural meaning.

The facility uses an adaptive optics system to correct for atmospheric disturbances and produce especially sharp images. The system works best under the clear night sky conditions that occur at this remote high elevation.

When both mirrors work together in interferometric mode, the facility achieves the observing power of a much larger single telescope measuring roughly 22.8 meters (74.8 feet) across. This technique combines light from both mirrors to reveal details that would otherwise stay invisible.

Location: Arizona

Elevation above the sea: 3,221 m

Diameter: 8.4 m

Part of: Mount Graham International Observatory, Steward Observatory

Website: http://lbto.org

GPS coordinates: 32.70131,-109.88906

Latest update: December 13, 2025 18:24