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NIST physicists Steve Jefferts (foreground) and Tom Heavner with the NIST-F2 cesium fountain atomic clock, a civilian time standard for the United States. NIST-F2 is a caesium fountain atomic clock that, along with NIST-F1, serves as the United States' primary time and frequency standard. [1] NIST-F2 was brought online on 3 April 2014. [1] [2]
NIST-F1, source of the official time of the United States. NIST-F1 is a cesium fountain clock, a type of atomic clock, in the National Institute of Standards and Technology (NIST) in Boulder, Colorado, and serves as the United States' primary time and frequency standard. The clock took fewer than four years to test and build, and was developed ...
The high frequency of caesium allows for more accurate measurements. Caesium reference tubes suitable for national standards currently last about seven years and cost about US$35,000. Primary frequency and time standards like the United States Time Standard atomic clocks, NIST-F1 and NIST-F2, use far higher power. [34] [70] [71] [72]
The other standard time and frequency reference for the U.S. Government is the National Institute of Standards and Technology (NIST) master clock. The U.S. Naval Observatory also maintains an alternate clock designated "USNO Alternate Master Clock" at Schriever Space Force Base , Colorado .
The primary time standard in the U.S. is currently NIST-F1, a laser-cooled Cs fountain, [34] the latest in a series of time and frequency standards, from the ammonia-based atomic clock (1949) to the caesium-based NBS-1 (1952) to NIST-7 (1993).
Time Protocol Network Time Protocol: pool.ntp.org: Computer with NTP client that syncs at least once an hour. ntpd, sntp, ntpdate: Meinberg NTP [23] NetTime [24] ToyNTP [16] BktTimeSync by IZ2BKT [17] NTPSec Precision Time Protocol: Domain Time II [25] NIST Telephone Time of Day Service [26] UTC(NIST) + 1-303-499-7111 + 1-808-335-4363; Voice ...
NIST‑F1 serves as the source of the nation's official time. From its measurement of the natural resonance frequency of cesium—which defines the second—NIST broadcasts time signals via longwave radio station WWVB near Fort Collins, Colorado, and shortwave radio stations WWV and WWVH, located near Fort Collins and Kekaha, Hawaii ...
Current events; Random article; About Wikipedia; ... NIST-F1, [7] Cs fountain 3.1 × 10 ... National Standard Time and Frequency Laboratory;