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, in cooperation with other institutions, has also provided timing for the United States and the international community. Its Master Clock (MC) is the source of UTC (USNO), USNO’s realization of Coordinated Universal Time (UTC), which has stayed within 5 ns rms of UTC since 1999 and within 3.1 ns rms in 2008. The data used to generate UTC (USNO) are based upon 70 cesium and 24 hydrogen maser frequency standards in four buildings at two sites. USNO disseminates time via voice, telephone modem, LORAN, 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://tycho.usno.navy.mil, which will shortly be transformed to http://www.usno.navy.mil.
Published in:	Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 4, 2008 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	605 - 622
Cite this article:	Matsakis, Demetrios, "Time and Frequency Activities at the U.S. Naval Observatory," Proceedings of the 40th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 2008, pp. 605-622.
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