Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, Altitude 2,606 m (8,550 ft) and at the Cerro Tololo Inter-American Observatory at an altitude of 2200 meters near La Serena, Chile.