The Directorate of Time, U.S. Naval Observatory is the official source of time for the Department of Defense and the standard of time for the United States.

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"The inaudible and noiseless foot of Time." --W. S.

The Directorate of Time is located at the U.S. Naval Observatory, Washington, DC.
Click here for a 295K GIF image of the Naval Observatory grounds.

"The Department of the Navy serves as the country's official timekeeper, with the Master Clock facility at the Washington Naval Observatory."
--National Defense Authorization Act for Fiscal years 1992 and 1993.

The U.S. Naval Observatory is established as the Department of Defense reference for time by DoD Instruction 5000.2, SECNAV Instruction 5000.2D, and OPNAV Instruction 5000.2

U. S. Naval Observatory timekeeping is based on an ensemble of cesium beam and hydrogen maser atomic clocks. Earth orientation parameters for timekeeping and navigation are observed using a network of radio telescopes. Astronomers, mathematicians, and computer geeks run the show. The need for extreme precision in timekeeping arises from many applications in communications and navigation.

Here is information on our History and Organization.

What time is it?

Time Service Department, Time Scales Division
...The USNO Time Scale, definitions of time, NAVSTAR GPS, Loran, OMEGA, rise/set times, computer operations, Automated Data Service

Precise Time and the USNO Master Clock
...Atomic clocks and the computation of the Master Clock time scale

Network Time Services
...NTP and other protocols for time over the Internet

Telephone time voice announcer.
...Our 900 number for all ages

Time via modem
...Programs and information on setting computer time via modem

Times of Sun/Moon Rise/Set in the U.S.
...is your home town in here?

Directorate of Time anonymous ftp server
...Grab all the free data you can get your hands on

Two-way Satellite Time Transfer
...Bouncing time off satellites to synchronize distant labs. It's cool stuff

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Alternate Master Clock, Schriever AFB, CO
...Major new timing facility

Unofficial list of World Time Zones

Links to other cool places

National Earth Orientation Service (NEOS)
...The Earth keeps wobbling, and we keep an eye on it

NIST
...National Institude of Standards and Technology
Astronomical Headlines from the International Astronomical Union
...The Central Bureau for Astronomical Telegrams & Minor Planet Center

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The information in this WWW service is subject to change or termination without notice.
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A serious note...

To learn about the U.S. Naval Observatory go up to the USNO Home Page