International Atomic Time

International Atomic Time

(TAI) The most precisely determined timescale now available, set up by the Bureau Internationale de l'Heure in Paris, following analysis of atomic time standards in many countries. It was adopted for all timing on Jan. 1 1972. The fundamental unit is the SI second. It is a more precise scale than can be determined from astronomical observations. Coordinated universal time is based on TAI and is used for all civil timekeeping. See also dynamical time.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

international atomic time

[¦in·tər¦nash·ən·əl ə¦täm·ik ′tīm]

(horology)

Time based on atomic clocks operating in conformity with the definition of the second as the International System unit of time. Abbreviated IAT.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

International Atomic Time

(time, standard)

(TAI) An international standard measurement of time based on the comparison of many atomic clocks. TAI is maintained by the Bureau International des Poids et Mesures (BIPM), the world's governing body for civil atomic time measurement. TAI is the basis for Coordinated Universal Time.

BIPM.

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