An observatory at an altitude of 2120 m on Kitt Peak in the Quinlan Mountains 90 km southwest of Tucson, Arizona. It was founded in 1958 and is now part of the National Optical Astronomy Observatory (NOAO). Its largest telescope is the 4-m Mayall Telescope, opened in 1973. The 3.5-m WIYN Telescope was opened in 1994. Other KNPO instruments are a 2.1-m reflector for optical and infrared observations, opened in 1964, and a 0.9-m reflector opened in 1960 but operated by the WIYN consortium since 2001. Also on Kitt Peak are two facilities of the National Solar Observatory: the McMath–Pierce Solar Telescope and SOLIS (Synoptic Optical Long-term Investigations of the Sun), a trio of solar instruments which began operation in 2004. Telescopes owned by other institutions are also sited at KPNO. These include the 1.3-m Robotically Controlled Telescope (RCT), a KPNO telescope from 1965 to 1995 but subsequently transferred to the RCT Consortium of five institutions and reopened in 2004; a 0.9-m reflector which was a KPNO telescope from 1966 to 1990 but was then transferred to the Southeastern Association for Research in Astronomy (SARA) consortium and reopened in 1995; the 0.6-m Burrell Schmidt of Case Western Reserve University, Ohio (originally opened in 1946 and moved to Kitt Peak in 1979); and a 25-m dish of the National Radio Astronomy Observatory’s VLBA network. The University of Arizona’s Steward Observatory and the MDM Observatory are also sited on Kitt Peak, but they are not part of KPNO.

http://www.noao.edu/kpno/ Official observatory website.