NOMAD (for Naval Observatory Merged Astrometric Dataset) is an
astrometriccatalog 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.