Page "Terrestrial Time" Paragraph 12

In 2000, the IAU very slightly altered the definition of TT by adopting an exact value for the ratio between TT and TCG time, as 1 − 6. 969290134 × 10 < sup >− 10 </ sup >.

( As measured on the geoid surface, the rate of TCG is very slightly faster than that of TT, see below, Relativistic relationships of TT.