PalomarLeiden

The Palomar-Leiden survey, often referred to as the Palomar–Leiden survey (PLS), was a collaborative effort between Palomar Observatory in California and Leiden Observatory in the Netherlands during the early 1960s. The project aimed to identify and catalog minor planets by combining wide-field photographic plates with precise astrometric measurements.

Methodology and workflow: Plates were taken with the Palomar 48-inch Schmidt telescope at the Palomar Observatory, covering large swaths of the sky. The photographic plates were then sent to Leiden for careful measurement and analysis, where moving objects were identified and their positions recorded. Objects detected in the plates were followed up to confirm and determine their orbits. The survey produced provisional designations that often included the “P-L” or “P-L-S” identifiers.

Output and impact: The Palomar–Leiden survey yielded a large number of asteroid discoveries and provided extensive astrometric data that improved the orbital determinations of many minor planets. The results were archived as a catalog of newly identified asteroids, some of which were later numbered and named. The survey is regarded as one of the most productive plate-based asteroid searches of its era and significantly expanded the known population of main-belt bodies at the time.

Legacy: The collaboration demonstrated the value of international cooperation in astronomy and established methodologies for plate-based asteroid searching that influenced later surveys. The Palomar and Leiden archives remain important historical resources for the study of minor planets, their orbits, and the history of asteroid discovery.