NOMAD

NOMAD (for Naval Observatory Merged Astrometric Dataset) is an astrometric catalog of stars gathered from surveys, with updated position information, produced by the US Navy. It is a follow-on to earlier US Navy efforts, such as USNO-A and USNO-B (USNO is for United States Naval Observatory). Navies and sea-going vessels have a traditional interest in accurate star charts as an aid to navigation.