Structure containing telescopes and other instruments for observing celestial objects and phenomena. Observatories can be classified by the part of the electromagnetic spectrum they can receive. Most are optical, observing in and near the region of the visible spectrum. Some are equipped to detect radio waves; others (space observatories) are Earth satellites and other spacecraft that carry special telescopes and detectors to study celestial sources of high-energy radiation (e.g., gamma rays, ultraviolet radiation, X-rays) from above the atmosphere. Stonehenge may have been an early predecessor of the optical observatory. Perhaps the first observatory that used instruments to accurately measure the positions of celestial objects was built circa 150 BC by Hipparchus. The first notable premodern European observatory was that at Uraniborg, built for Tycho Brahe in 1576. Observatory House, in Slough, Eng., built and operated by William Herschel (see Herschel family), was one of the technical wonders of the 18th century. Today the world's largest groupings of optical telescopes are atop Mauna Kea, in Hawaii, and Cerro Tololo, in Chile. Other major observatories include Arecibo Observatory; Mount Wilson Observatory; Palomar Observatory; and Royal Greenwich Observatory.
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Astronomical observatory, oldest scientific institution in Britain, founded for navigational purposes in 1675 by Charles II at Greenwich, England. Its main contributions have been in navigation, timekeeping, determination of star positions, and almanac publication. In 1767 it began publishing The Nautical Almanac, based on the time at the longitude of Greenwich; its popularity among navigators led in part to the Greenwich meridian's being made Earth's prime meridian and the starting point for international time zones in 1884 (see Greenwich Mean Time).
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Astronomical observatory located atop Mount Wilson, near Pasadena, California, U.S. Founded in 1904 by George Ellery Hale (1868–1938), it was operated jointly with Palomar Observatory as Hale Observatories (1948–80). Its largest optical telescope, with a diameter of 100 in. (2.5 m), enabled Edwin Hubble and his associates to discover evidence of an expanding universe and to estimate its size.
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Astronomical observatory near Arecibo, P.R., site of the world's largest single-unit radio telescope (as opposed to multiple telescope interferometers such as the Very Large Array). The telescope dish, 1,000 ft (300 m) across, is built into a valley; celestial sources are tracked across the sky by moving secondary structures suspended about 500 ft (150 m) above the dish. The observatory has produced detailed radar maps of the surface of Venus and near-Earth asteroids (see Earth-crossing asteroid), made detailed studies of Earth's ionosphere, and made major contributions to studies of pulsars and hydrogen gas in galaxies.
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The Uppsala Astronomical Observatory (UAO; Astronomiska observatoriet i Uppsala) is an astronomical observatory in Sweden. It was founded in 1741, though there was a professorial chair of astronomy at the University of Uppsala from 1593 and the university archives include lecture notes in astronomy from the 1480s.
In the 18th century, Anders Celsius performed his research there and built the first observatory proper in 1741. Celsius managed to get the university consistory to buy a large stone house of medieval origin in central Uppsala, where he had an observatory constructed on the rooftop. Celsius both worked and had his personal living quarters in the house. This observatory remained in use until the new observatory, now known as the "old observatory", was built in 1853. The Celsius house itself still remains as one of few older buildings on a modern shopping street, but the observatory on the roof was demolished in 1857.
In the 19th century Anders Jonas Ångström was keeper of the observatory and conducted his experiments in astronomy, physics and optics there. His son, Knut Ångström, also conducted research on solar radiation at the observatory.
In 2000 the observatory merged with the Institute of Space Physics to form a Department of Astronomy and Space Physics and moved to the Ångström Laboratory. In addition to facilities in Uppsala, the observatory maintains the Kvistaberg Observatory in Sweden and the Uppsala Southern Station at Mount Stromlo and Siding Spring Observatory in Australia.
Research at the observatory over the years includes stellar parallaxes, stellar statistics, galactic structure, external galaxies, stellar atmospheres and solar system research.