National Radio Astronomy Observatory (NRAO), federal observatory for radio astronomy, founded in 1956 and operated under contract with the National Science Foundation by Associated Universities, Inc., a group of major universities. The headquarters are at Charlottesville, Va.; the original observatory site is in Greenbank, W.Va., where the antennas, or radio telescopes, include a fully steerable 328-ft (100-m) off-axis paraboloid with an adjustable surface, the world's largest fully steerable radio telescope; a fully steerable 140-ft (43-m) paraboloid; an interferometer consisting of three steerable 85-ft (26-m) paraboloids; and other radio telescopes. At Kitt Peak, near Tucson, Ariz., NRAO has a 36-ft (11-m) steerable paraboloid; near Socorro, New Mexico, the NRAO's Very Large Array (VLA) consists of 27 parabolic dishes, each 82 ft (25 m) in diameter, mounted on a Y-shaped track with arms up to 14 mi (21 km) long. Finally, the observatory operates the Very Baseline Array (VLBA) consisting of ten radio telescopes placed around the earth that operate in unison. The antenna sites are located in New Hampshire, Iowa, Saint Croix, Texas, New Mexico (two antennas), Arizona, California, Washington, and Hawaii; the headquarters is located at Socorro. The NRAO also is the lead North American partner in the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile (see European Southern Observatory). Principal research programs of the NRAO include the study of galactic structure, extragalactic radio sources, molecules in space, pulsars, quasars, and the evolution of stars and galaxies. Astronomers using the VLA have discovered filaments, jets, and high-temperature features in the center of our own galaxy and in extragalactic radio sources that may help explain the high energy of quasars. The system allows the study of the nuclei of active galaxies and helps determine distances to radio sources more accurately.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.