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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.<ref name="Leverington-2003" /><ref name="Gehrels-1994" /><ref name="Barnes-Svarney-2003" /><ref name="Levy-2002" /> The program is responsible for the discovery of 95 near-Earth Objects including 17 comets,<ref name="Helin-1997" /> while the Minor Planet Center directly credits PCAS with the discovery of 20 numbered minor planets during 1993–1994.<ref name="MPC-Discoverers" /> PCAS ran for nearly 25 years until June 1995. It had an international extension, INAS, and was the immediate predecessor of the outstandingly successful NEAT program.<ref name="Helin-1997" />
Notable discoveriesEdit
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,<ref name="MPC-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 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.<ref name="MPC-Wilson-Harrington" /> It was the first confirmation that a comet can evolve into an asteroid after it has degassed.<ref name="Helin-1997" />
List of discovered minor planetsEdit
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ReferencesEdit
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PublicationsEdit
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