Time and Frequency Division

NIST Physics Laboratory home page go to NIST home page
About the Division

The Time and Frequency Division, part of NIST's Physics Laboratory, maintains the standard for frequency and time interval for the United States, provides official time to the United States, and carries out a broad program of research and service activities in time and frequency metrology.
- What we do
- Postdoctoral Opportunities
- A Walk Through Time
- Division History
- FAQ
- Time and Frequency from A to Z:
An illustrated glossary
- Publications
- Seminars
- Staff directory

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Services

The division broadcasts standard time and frequency signals using radio, Internet, and telephone links. These signals synchronize millions of clocks every day.
   
- Internet Time Service
- Radio Station WWVB
- Radio Station WWV
- Radio Station WWVH
- Telephone Time
- Frequency Measurement Service
- GPS Data Archive
- NOTICE: GOES Time Code Service to End on January 1, 2005

Standards

The division develops and maintains the primary standards for frequency and time interval in the United States.

- NIST-F1 Cesium Fountain Atomic Clock
- Primary Atomic Reference Clock in Space
- NIST Time Scale Data and Bulletin Archive

Metrology

The division maintains advanced measurement and calibration facilities for characterizing noise components in oscillators and frequency synthesizers.
   
- Time and Frequency Metrology Group
- Measurement Systems Tutorial

Research

The division's ongoing research programs are leading the way to the next generation of time and frequency standards and measurements.
   
- Ion Storage Group
- Optical Frequency Measurements Group
Privacy Policy / Security Notice
Disclaimer / FOIA

NIST is an agency of the
U.S. Commerce Department's
Technology Administration.

Online: 1995
Last update: September 2004
clock link to NIST time
The Official
United States Time

Information about WWVB
Radio-Controlled Clocks
Optical Clockwork
New Optical Clock Promises More Accuracy than Cesium. NIST researchers have demonstrated a new kind of atomic clock that has the potential to be up to 1,000 times more accurate than today's best clock. The new clock is based on an energy transition in a single trapped mercury ion (a mercury atom that is missing one electron). Building a clock based on such a high-frequency transition was previously impractical because it requires both "capturing" the ion and holding it very still to get accurate readings, and having a mechanism that can "count" the ticks accurately at such a high frequency.

The quality of a clock depends on its stability and accuracy—whether the clock provides a constant, unchanging output frequency, and how close the measured frequency is to the fundamental atomic resonance that provides the clock's "tick." One advantage of the new clock is that it ticks much faster. Today’s international time and frequency standards, such as NIST-F1, measure an atomic resonance of about 9 billion cycles per second. By contrast, the new NIST device monitors an optical frequency more than 100,000 times higher or about 1 quadrillion (US) cycles per second.
National Institute of Standards and Technology
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Boulder, CO 80305

Web site comments and general technical questions: Michael Lombardi
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