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.
[2][3][4][5] The program is responsible for the discovery of 95 near-Earth Objects including 17 comets,[6] while the Minor Planet Center directly credits PCAS with the discovery of 20 numbered minor planets during 1993–1994.
It had an international extension, INAS, and was the immediate predecessor of the outstandingly successful NEAT program.
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.