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The USNO websites aa.usno.navy.mil, ad.usno.navy.mil, aristarchus.usno.navy.mil, maia.usno.navy.mil, rorf.usno.navy.mil, and toshi.usno.navy.mil are undergoing modernization efforts. The expected completion of the work and return of service is estimated as 30 April 2020. Please submit a requirements form to the USNOPAO if the information you are seeking is not accessible via other means.
 

About The U.S. Naval Observatory

NOTICE

This US Naval Observatory Website is undergoing modernization and will be offline starting Thursday, 24 October 2019.   The expected completion of work and return of service is estimated as 30 April 2020.  Please visit usno.navy.mil and submit a Requirements Form to the USNO PAO if the information you are seeking is not accessible via another means.

 

The United States Naval Observatory is an Echelon-IV 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

The U.S. Naval Observatory performs an essential scientific role for the United States, the Navy, and the Department of Defense. 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: Astrometry, Astronomical Applications, Earth Orientation, and Time Service. Each Department is responsible for specific products and services tailored to our end-users within both the DoD and civilian worlds.

USNO Master Clock Time
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