Time and Frequency Activities at the U.S. Naval Observatory

Demetrios Matsakis

Abstract:	The U.S. Naval Observatory (USNO) has provided timing for the Navy since 1830 and, via DoD Directive 4650.05, is the sole source of timing for the Department of Defense. In cooperation with other institutions, the USNO also provides timing for the United States and the international community. Its Master Clock (MC) is the source ofUTC (USNO), USNO’s realization of Coordinated Universal Time (UTC), which has stayed within 5 ns rms of UTC since 1999 and within 4 ns rms in 2010. The data used to generate UTC (USNO) are based upon 69 cesium and 26 hydrogen maser frequency standards in four buildings at two sites. USNO disseminates time via voice, telephone modem, Network Time Protocol (NTP), GPS, and Two-Way Satellite Time Transfer (TWSTT). This paper describes some of the changes being made to meet the future needs for precision, accuracy, and robustness. Further details and explanations of our services can be found online at http://www.usno.navy.mil/USNO.
Published in:	Proceedings of the 42nd Annual Precise Time and Time Interval Systems and Applications Meeting November 15 - 18, 2010 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	11 - 32
Cite this article:	Matsakis, Demetrios, "Time and Frequency Activities at the U.S. Naval Observatory," Proceedings of the 42nd Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, November 2010, pp. 11-32.
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