IERS Rapid Service / Prediction Center

Delta T


Monthly determinations of Delta T (TT - UT1) since 1973
Long-term predictions of Delta T (TT - UT1) from
Historic Delta T and LOD values from McCarthy and Babcock (1986)


The DeltaT files provided by the Rapid Service/Prediction Center are the difference between time determined from the Earth's rotation and a more uniform time scale, such as Ephemeris Time or Terrestrial Time. The files available here are of lower precision than the daily updated Earth Orientation Parameter files, such as finals.daily and finals2000A.daily.