Palomar-Leiden Survey

The Palomar-Leiden Survey (PLS) was a 1960s astronomical survey in search of distant minor planets. Plates of the target-portion of the celestial sphere were carried out with the Palomar Observatory Palomar 48 Schmidt camera, the plates then analyzed (i.e., comparisons looking for moving objects) at Leiden Observatory in the Netherlands. Three subsequent surveys in the 1970s (Palomar-Leiden Trojan surveys 1, 2, and 3: T-1, T-2, and T-3) specifically searched for Trojan asteroids, which also included contributions by other observatories. Over 4000 minor planets were discovered.