United States Naval Observatory

The U.S. 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 War, and a standard of time for the entire U.S. Founded in 1830 as the U.S. Navy Depot of Charts and Instruments, USNO is recognized as the world's foremost authority on spatial and temporal reference frames. USNO is headquartered in Washington, D.C., and operates a dark-sky observing station near Flagstaff, Arizona (NOFS). It also has a small detachment activity, the Alternate Master Clock facility (AMC), located at Schriever Space Force Base in Colorado Springs, Colorado The U.S. Naval Observatory (USNO) serves as DoD's authoritative source for the positions and motion of celestial bodies, motions of the Earth, and precise time. USNO provides tailored products, performs relevant research, develops leading edge technologies and instrumentation, and operates state of the art systems in support of the U.S. Navy, DoD, Federal Agencies, international partners, and the general public. The **United States Naval Observatory** is an Echelon-IV operational command reporting to the [Commander, Naval Meteorology and Oceanography Command](https://www.cnmoc.usff.navy.mil/). The Observatory's headquarters are located in Washington, DC, with field activities located at the [Naval Observatory Flagstaff Station (NOFS)](https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/The-Naval-Observatory-Flagstaff-Station/) in Flagstaff, AZ and the USNO Alternate Master Clock (AMC) located at [Schriever Space Force Base](https://www.schriever.spaceforce.mil/) near Colorado Springs, CO. The U.S. Naval Observatory performs an essential scientific role for the United States, the Navy, and the Department of War. Its mission includes determining the positions and motions of the Earth, Sun, Moon, planets, stars and other celestial objects; providing astronomical data; determining precise time; measuring the Earth's rotation; and maintaining the Master Clock for the United States. Observatory astronomers formulate the theories and conduct the relevant research necessary to improve these mission goals. This astronomical and timing data, essential for accurate navigation and the support of communications on Earth and in Space, is vital to the Navy and Department of Defense. It is also used extensively by other agencies of the government and the public at large. The Observatory consists of four Scientific Departments: [**Astronomical Applications**](https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/Astronomical-Applications-Department/), [**Celestial Reference Frames**](https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/Celestial-Reference-Frame-Department/), [**Earth Orientation**](https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/Earth-Orientation-Department/), and [**Precise Time**](https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-Naval-Observatory/Precise-Time-Department/). Each Department is responsible for specific products and services tailored to our end-users within both the DoD and civilian worlds.