This public service is cooperatively provided by the two time agencies of the United States: a Department of Commerce agency, the National Institute of Standards and Technology (NIST), and its military counterpart, the U. S. Naval Observatory (USNO). Readings from the clocks of these agencies contribute to world time, called Coordinated Universal Time (UTC). The time maintained by both agencies should never differ by more than 0.000 0001 seconds from UTC.

If you are a navigator, or just wish to set your watch to provide the correct time, check often. As a navigator, be sure to track the amount by which your clock/watch differs from this time. This will allow you to compensate when you are out-of-touch with a standard time.

Official Time URL