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FTP server of the BIPM Time Department
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Circular T
UTCr
TT(BIPM)
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TT(BIPM) is a realization of Terrestrial Time as defined by the International Astronomical Union (IAU). It is computed annually by the BIPM, based on a weighted average of the evaluations of the frequency of TAI by the primary and secondary frequency standards. It is mostly used in scientific applications requiring long-term frequency stability and high frequency accuracy.


Last computed TT(BIPMXY) and older computations can be accessed below :
(Each computation is identified by the string XY where 19XY or 20XY is the last year of data included)
    TT(BIPMXY)
    View


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International metrology publications
SI Brochure
Guides in metrology
Metrologia
Circular T
IERS Conventions Center
Recommended values of standard frequencies
Related articles
International reference timescales
Recent publications of the BIPM Time Department