An observatory jointly owned by the Smithsonian Institution and the University of Arizona, located at an altitude of 2616 m on Mount Hopkins, Arizona, in the grounds of the Fred Lawrence Whipple Observatory. It operates the MMT, a telescope with a 6.5-m mirror, opened in 2000. This replaced the original Multiple Mirror Telescope at the same observatory, which operated from 1979 to 1998. The original MMT consisted of six 1.8-m mirrors on a single mounting, giving a collecting area equivalent to one 4.5-m mirror. Although the new telescope uses a single mirror, the MMT name has been retained.

http://www.mmto.org/ Official observatory website.