U.S. Naval Observatory

The U.S. Naval Observatory (USNO), a scientific and military facility under the Department of Defense, is the authoritative source for positioning, navigation, and precise timing data. USNO determines the positions and motions of celestial bodies, Earth's orientation, and maintains the Master Clock for the U.S., crucial for accurate navigation in space and supporting communications. It provides astronomical data, reference frames, and timing information to the Navy, DoD, other government agencies, and the public, and collaborates with international scientific establishments.