Nicholas U. Mayall 4-meter Telescope


The Kitt Peak National Observatory is located on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O'odham Nation. With over twenty optical and two radio telescopes, it is one of the largest gatherings of astronomical instruments in the northern hemisphere.

The Nicholas U. Mayall 4-meter Telescope, named for the former Director of the Kitt Peak National Observatory, was the second-largest telescope by aperture at the time of its first light in 1973. The eighteen-story telescope, located just below the summit of Kitt Peak, can be seen from over fifty miles away. Today it is the largest at Kitt Peak National Observatory. The facility is well known for discovering methane ice on Pluto.

The Mayall telescope currently hosts the Dark Energy Spectroscopic Instrument (DESI), the most powerful multi-object survey spectrograph in the world. DESI is supported by the Department of Energy Office of Science. The DESI project and the operations of the survey are led by the Lawrence Berkeley National Laboratory.

For scientists: More details can be found on the science page.


Nicholas U. Mayall 4-meter Telescope

Name(s) Nicholas U. Mayall 4-meter Telescope
Status Operational
Broad Science Goals

Wide-field optical and infrared imaging and spectroscopy to 2018

DESI multi-object optical spectroscopy since 2019

Site Kitt Peak National Observatory, Arizona, USA
Location Coordinates 111º 35’ 59.6’S
31º 57’ 50.50’E
Altitude 2120m
Optical Design Ritchey-Chretien Reflector Telescope
Field of View 3 degrees (DESI)
Diameter: Primary M1 4.0 m; masked to 3.797 m
Material: Primary M1 Fused quartz
Diameter: Secondary M2 1192 mm (prior to DESI installation)
Material: Secondary M2  
Mount The equatorial mounting has an inclination of 32 degrees with a "horseshoe" bearing (right ascension, parallel to earth's axis) and a perpendicular bearing (declination)
First Light Date 1973
Adaptive Optics None
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