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Prehistory of the IERS, up to 1986


  • precession known since antiquity
  • ca. 1543: the rotating earth as part of the Copernican world system
  • 1744: nutation discovered by James Bradley
  • 1765: polar motion predicted by Leonhard Euler
  • around 1890: observational evidence for polar motion (Friedrich Küstner, Seth Chandler)
  • 1895: International Latitude Service (ILS) founded
  • 1899: ILS started its regular operation
  • 1919: Bureau International de l'Heure (BIH) founded
  • BIH becomes responsible for the coordination of Universal Time (UT)
  • 1955: Service International Rapid (SIR) established by BIH, including an own polar motion determination
  • 1962: ILS was superseded by the International Polar Motion Service (IPMS) by including independent stations
  • 1980ies: Project MERIT (Monitor Earth Rotation and Intercompare the Techniques of observation and analysis)
  • 1986: proposals for a new International Earth Rotation Service, prepared at a MERIT Workshop

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