National Geographic Society – Palomar Observatory Sky Survey

The National Geographic Society – Palomar Observatory Sky Survey (NGS-POSS, or just POSS, also POSS I) was a major astronomical survey, that took almost 2,000 photographic plates of the night sky. It was conducted at Palomar Observatory, California, United States, and completed by the end of 1958.

Source: Wikipedia — National Geographic Society – Palomar Observatory Sky Survey (CC BY-SA 4.0)