Nicholas U. Mayall Telescope

The Nicholas U. Mayall Telescope is an optical instrument with a 4-meter primary mirror made of fused quartz, located at 2,120 meters elevation at Kitt Peak National Observatory. The facility operates multiple focal points and houses the Dark Energy Spectroscopic Instrument, which uses roughly 5,000 fiber optic sensors.

The telescope was inaugurated in 1973 and was the second-largest of its kind in the world at that time. It later contributed to the discovery of methane ice on Pluto in 1976.

The observatory sits on land belonging to the Tohono O'odham Nation, showing how modern science and Native American territories coexist. Walking through the site, visitors experience this relationship between research and the indigenous community.

The visitor area sits at high elevation in a dry mountain region, so bring plenty of water and sun protection when visiting. The best time to visit is in the afternoon when the sun is lower and conditions become more comfortable.

The structure rises about 18 stories high and is visible from great distances across the Arizona-Sonora Desert. This striking silhouette makes the telescope a notable landmark in the high desert landscape.

Location: Arizona

Official opening: 1973

Elevation above the sea: 2,120 m

Diameter: 4 m

Part of: Kitt Peak National Observatory

Website: https://noirlab.edu/public/programs/kitt-peak-national-observatory/nicholas-mayall-4m-telescope

GPS coordinates: 31.96340,-111.60000

Latest update: December 10, 2025 20:06