Atomic Time
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Edoardo Salazar

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World Time and ClocksWorld Time and Clocks - Clocks are found all over the world and all tell you the same thing wherever you live. We've gathered information about world time and clocks. Things like daylight savings time, world time zones, atomic clocks & more.

International Atomic Time is a high precision time standard that tracks proper time on Earth's geoid. It is the principal realisation of Terrestrial Time.

International Atomic Time

TAI, from the French name Temps Atomique International is a high precision time standard that tracks proper time on Earth's geoid. It is the principal realisation of Terrestrial Time, and the basis for Coordinated Universal Time (UTC) which is used for civil timekeeping all over the Earth's surface. As of 2006 TAI is exactly 33 seconds ahead of UTC: 10 seconds initial difference at the start of 1972, plus 23 leap seconds in UTC since 1972.

The atomic time as a frequency standard is a weighted average of the time kept by about 300 atomic clocks in over 50 national laboratories worldwide. Many of these are caesium atomic clocks, which are the standard by which the SI second is defined. Due to the averaging it is far more stable than any clock would be alone.

The clocks at different institutions are regularly compared against each other. The International Bureau of Weights and Measures (BIPM) combines these measurements to retrospectively calculate the weighted average that forms the most stable time scale possible. This combined time scale is published monthly in Circular T, and is the canonical TAI. This time scale is expressed in the form of tables of differences UTC-UTC(x) and TAI-TA(x), for each participating institution x. Wikipedia

The most relevant links we could find, placed here free

Atomic Time - The home of radio-controlled atomic clocks and atomic watches, online orders, shipping services to continental US.

World Time Server - Atomic clock time sync information.

AtomTime - AtomTime Pro is a Windows application which will connect to the Atomic Clock time server in Boulder, Colorado (USA) via the Internet and fetch the current atomic clock time value.

BIPM - Site of the Bureau International des Poids et Mesures from France. Additional information about TAI.

Atomic clock (Click to enlarge)
Atomic clock

Atomic clocks work by measuring how atoms vibrate. The atomic time was not adopted until 1972 as the primary reference for all scientific timing.

The Coordinated Universal Time (UTC) is an atomic time scale derived from TAI, to provide a reference scale in step with the irregular rotation of the earth. Local realizations of UTC exist at the national time laboratories. These laboratories participate in the calculation of the international time scales by sending their clock data to the BIPM. BIPM

Atomic time watch (Click to enlarge)
Atomic time watch

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