International Atomic Time
The International Atomic Time (TAI for French Temps Atomique International) is an atomic time scale, the coordination by national atomic time ( TA) is determined.
Worldwide contribute to TAI over 60 different time institutions with currently about 260 atomic clocks at. The national atomic time TA ( PTB) in Germany is determined by the atomic clocks of the Physikalisch-Technische Bundesanstalt ( PTB). The coordination of the TAI is the responsibility of the International Bureau of Weights and Measures.
The TAI is an atomic time, ie it is based on an atomic time standard, namely the SI second. Thus, it comes according to a shift between the TAI and solar time. As in everyday life are more time scales of interest, which are synchronous to solar time, the TAI rarely makes its appearance in everyday life. Of practical importance, for example, the Coordinated Universal Time (UTC). For relationship between atomic time and UTC see also the article atomic time.
The International Atomic Time was set so that the start time January 1, 1958 0:00 clock TAI astronomical time scale UT1 is approximately equal.
Reference TAI -UTC
The TAI is going on with respect to the UTC. The difference between TAI and UTC was 2012 35 seconds on July 1. The insertion of leap seconds in UTC, this difference may change.