In asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 naming, the designation P–L stands for Palomar–Leiden, named after Palomar Observatory

Palomar Observatory

Palomar Observatory is a privately owned observatory located in San Diego County, California, southeast of Pasadena's Mount Wilson Observatory, in the Palomar Mountain Range. At approximately elevation, it is owned and operated by the California Institute of Technology...

 and Leiden Observatory

Leiden Observatory

Leiden Observatory is an astronomical observatory in the city of Leiden, Netherlands. It was established by Leiden University in 1633, to house the quadrant of Snellius, and is the oldest operating University observatory in the world Leiden Observatory (Sterrewacht Leiden in Dutch) is an...

, the observatories at which asteroid searchers Tom Gehrels

Tom Gehrels

Tom Gehrels , was an American astronomer, Professor Planetary Sciences, and Astronomer at the University of Arizona, Tucson....

 of the University of Arizona

University of Arizona

The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...

, Ingrid van Houten-Groeneveld

Ingrid van Houten-Groeneveld

Ingrid van Houten-Groeneveld is a Dutch astronomer.In a jointly-credited trio with Tom Gehrels and her husband Cornelis Johannes van Houten, she was an extremely prolific discoverer of many thousands of asteroids...

 and Ingrid's husband Cornelis Johannes van Houten

Cornelis Johannes van Houten

Cornelis Johannes van Houten was a Dutch astronomer, sometimes referred to as Kees van Houten.Born in The Hague, he spent his entire career at Leiden University except for a brief period as research assistant at Yerkes Observatory...

 of the Netherlands collaborated on a famously fruitful asteroid search in the 1960s.

Gehrels used Palomar's 48-inch Schmidt camera

Schmidt camera

A Schmidt camera, also referred to as the Schmidt telescope, is a catadioptric astrophotographic telescope designed to provide wide fields of view with limited aberrations. Other similar designs are the Wright Camera and Lurie-Houghton telescope....

and shipped the photographic plates to Leiden. The trio are credited with several thousand asteroid discoveries.