Leiden Observatory
The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis Johannes van Houten and Ingrid van Houten-Groeneveld at Leiden Observatory. The trio are credited with several thousand asteroid discoveries.