NATIONAL RADIO ASTRONOMY OBSERVATORY

(NRAO) the national radio observatory of the United States. It is funded by the National Science Foundation and is managed by Associated Universities, Inc., a consortium of nine leading private universities. Its headquarters are in Charlottesville, Va. The NRAO was established in the mid-1950s and acquired its first operational radio telescope in 1959. It now has three principal observing facilities: at Green Bank, W.Va.; at Kitt Peak, near Tucson, Ariz.; and at a site 50 miles (80 km) west of Socorro, N.M. The NRAO was originally headquartered at the Green Bank site, whose chief instrument was a 91-metre (300-foot) partially steerable radio telescope that was completed in 1962 but which inexplicably collapsed in 1988. Its replacement, the Green Bank Telescope, which was scheduled to enter operation in 1998, will have an aperture of 100 m (330 feet) and will be one of the world's largest fully steerable radio telescopes. The NRAO has several other important radio telescopes. The Very Large Array (q.v.), near Socorro, is one of the most powerful radio telescopes in the world. The Very Long Baseline Array (VLBA) is an array of 10 identical 25-metre radio telescopes spread across the United States that are used for very long baseline interferometry.