United States Naval Observatory

The United States Naval Observatory (USNO) provides a wide range of astronomical data and products, and serves as the official source of time for the U.S. Department of Defense and a standard of time for the entire United States. The United States Naval Observatory is a fourth echelon operational command reporting to the Commander, Navy Oceanography and Meteorology Command. The Observatory's headquarters are located in Washington, DC, with field activities located at the Naval Observatory Flagstaff Station (NOFS) in Flagstaff, AZ and the USNO Alternate Master Clock located at Schriever Air Force Base near Colorado Springs, CO.