– the intergovernmental organization through which Member States act together
     on matters related to measurement science and measurement standards.
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IERS (International Earth Rotation and Reference Systems Service)

The International Earth Rotation and Reference Systems Service (IERS) was established in 1987 by the International Astronomical Union and the International Union of Geodesy and Geophysics. Intially called the "International Earth Rotation Service", it was renamed "International Earth Rotation and Reference Systems Service" in 2003.

The primary objectives of the IERS are to serve the astronomical, geodetic and geophysical communities by providing:

  • the International Celestial Reference System (ICRS) and its realization, the International Celestial Reference Frame (ICRF);
  • the International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF);
  • Earth orientation parameters required to study Earth orientation variations and to transform between the ICRF and the ITRF;
  • monitoring of the difference between UT1 and UTC and announcing the insertion of leap seconds;
  • geophysical data to interpret space/time variations in the ICRF, ITRF or Earth orientation parameters, and model such variations;
  • standards, constants and models (i.e., conventions) encouraging international adherence.

Links between the BIPM and the IERS:

  • The IERS decides on the dates of application of leap seconds on UTC.

BIPM contact(s):
IERS contact(s):
  • Dr Brian Luzum, Chair, IERS Directing Board