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)



For more information please see the Readme file

Older files can be accessed directly from the ftp server at https://webtai.bipm.org/ftp/pub/tai/ttbipm/.