An astronomical survey is a general map or image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of images, spectra, or other observations of objects that share a common type or feature. Surveys are often restricted to one band of the electromagnetic spectrum due to instrumental limitations, although multiwavelength surveys can be made by using multiple detectors, each sensitive to a different bandwidth.
6-583: The Palomar Planet-Crossing Asteroid Survey ( PCAS ) was an astronomical survey , initiated by American astronomers Eleanor Helin and Eugene Shoemaker at the U.S Palomar Observatory , California, in 1973. The program is responsible for the discovery of 95 near-Earth Objects including 17 comets , while the Minor Planet Center directly credits PCAS with the discovery of 20 numbered minor planets during 1993–1994. PCAS ran for nearly 25 years until June 1995. It had an international extension, INAS , and
12-495: A hypothesis, a telescope scheduling committee is more likely to approve new, more detailed observations to test it. The wide scope of surveys makes them ideal for finding foreground objects that move, such as asteroids and comets. An astronomer can compare existing survey images to current observations to identify changes; this task can even be performed automatically using image analysis software. Besides science, these surveys also detect potentially hazardous objects , providing
18-623: A result, these objects have a particularly high probability of colliding with the Earth . In 1979, Helin discovered an Apollo-type asteroid, that they later identified with the comet 4015 Wilson–Harrington . It was the first confirmation that a comet can evolve into an asteroid after it has degassed. Astronomical survey Surveys have generally been performed as part of the production of an astronomical catalog . They may also search for transient astronomical events . They often use wide-field astrographs . Sky surveys, unlike targeted observation of
24-570: A service to Spaceguard . For example, the Asteroid Terrestrial-impact Last Alert System (ATLAS) system surveys the entire night sky every night and, like NEOSTEL , is intended to detect objects as they approach. Broader surveys include the Uppsala–DLR Asteroid Survey and the 20th-century U.K. Schmidt–Caltech Asteroid Survey . Old surveys can be reviewed to find precovery images. Similarly, images of
30-453: A specific object, allow astronomers to catalog celestial objects and perform statistical analyses on them without complex corrections for selection effects . In some cases, an astronomer interested in a particular object will find that survey images are sufficient to make new telescope time entirely unnecessary. Surveys also help astronomers choose targets for closer study using larger, more powerful telescopes. If previous observations support
36-484: Was the immediate predecessor of the outstandingly successful NEAT program . The first NEO discovered by PACS was (5496) 1973 NA , an Apollo asteroid with an exceptional orbital inclination of 68 ° , the most highly inclined minor planet known until 1999. In 1976, Eleanor Helin discovered 2062 Aten , the first of a new class of asteroids called the Aten asteroids with small orbits that are never far from Earth's orbit. As
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