You are here: Home USNO Earth Orientation Earth Orientation Products Weekly Solutions Bulletin A

Bulletin A

    IERS Bulletin A reports the latest determinations for polar motion, UT1-UTC, and celestial pole offsets at daily intervals based on a combination of contributed analysis results using data from Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Positioning System (GPS) satellites, and Lunar Laser Ranging (LLR). Predictions for up to a year into the future are also provided. Meteorological predictions of variations in Atmospheric Angular Momentum (AAM) are used to aid in the prediction of near-term UT1-UTC changes. This publication is prepared by the IERS Rapid Service/Prediction Center.


  • latest issue of IERS Bulletin A -- currently updated weekly (Thursday);
    the contents are described in the Publications (Scientific Publications).  To subscribe to the IERS Bulletin A use the document request form.
  • Prediction coefficients only
  • Contents of Bulletin A
  • External archive of past issues of Bulletin A
USNO Master Clock Time
Javascript must be Enabled