Orbiting Astronomical Observatory


Orbiting Astronomical Observatory

(OAO), series of four orbiting observatories (see observatory, orbitingobservatory, orbiting,
research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects of the earth's environment interfere with astronomical observations from the
..... Click the link for more information. ) launched between 1966 and 1972 by the National Aeronautics and Space Administration (NASA) to provide astronomical data in the ultraviolet and X-ray wavelengths filtered out by the earth's atmosphere. Only two of the four launches were successful, however. OAO-2, launched in 1978, which carried two large telescopes in addition to a cluster of four ultraviolet telescopes, four photoelectric telescopes, and a number of spectrometers and other devices, weighed 4,200 lb (1,900 kg) and was the heaviest satellite orbited to that time. Working primarily with ultraviolet radiation, it was able to photograph very young stars. OAO-3, which was also called Copernicus, was launched in 1972. Carrying what was at that time the largest telescope ever orbited and three smaller X-ray telescopes, OAO-3 was primarily used in the study of ultraviolet radiation from interstellar gas and dust and from stars near the edges of the Milky Way. See also ultraviolet astronomyultraviolet astronomy,
study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measurements are used to discern the chemical composition, densities, and temperatures
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Orbiting Astronomical Observatory

(OAO) Any of a series of four US satellites, two of which were successfully launched, that were primarily concerned with investigations in the ultraviolet (UV) region of the spectrum. OAO–2 was launched on Dec. 7 1968 and continued operating for over four years. In one group of experiments a UV survey of about one sixth of the sky was achieved by means of four telescopes plus UV-sensitive television camera tubes, which produced pictures in the wavelength range 115–320 nm. A catalogue of bright UV sources was compiled from the data. In the other experimental package measurements were made of the UV luminosity and spectra of a large number of preselected targets. OAO–3 was launched on Aug. 21 1972 and was named Copernicus after launch.