United States Naval Observatory (USNO) | 1,860 followers on LinkedIn. Sky and Ocean Joined | 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, Naval Meteorology and Oceanography Command.