Multiple Mirror Telescope (MMT)
The Multiple Mirror Telescope (MMT) is a 6.5-meter telescope located at an altitude of 2,606 meters (8,550 feet) on the summit of Mount Hopkins, the second highest peak in the Santa Rita Range of the Coronado National Forest, about 55 kilometers south of Tucson, Arizona, on the grounds of the Smithsonian's Fred Lawrence Whipple Observatory. In 1998, the large single mirror replaced six identical 1.8-meter mirrors on a common mount (with a combined light-collecting power of a 4.5-meter mirror), which had been in use since 1979. Just before it was upgraded, the old MMT was used in a pioneering demonstration of nulling interferometry to image the dust cloud around Betelgeuse. The MMT is a joint venture of the University of Arizona, which operates the MMT, and the Smithsonian Institution.