U.S. Naval Observatory Earth Orientation Department

The Earth Orientation Parameters (EOP) Analysis and Prediction Program produces and distributes high-quality Earth orientation data and their predictions. Data from any useful technique (Very Long Baseline Interferometry, Global Positioning System, laser ranging, etc.) are combined to provide polar motion, UT1, precession and nutation in near real time. Predictions are produced from these determinations.

As a participant in the National Earth Orientation Service (NEOS), the Earth Orientation Department also serves as the Sub-bureau for Rapid Service and Predictions of the International Earth Rotation and Reference Systems Service (IERS). EOP results are distributed semi-weekly in the IERS Bulletin A by e-mail and by surface mail. The service is updated daily and is available continuously using the Internet protocols http/ftp. If you would like to regularly receive EOP data, please fill out and submit a product request form (requires a 'forms' capable browser).

Department personnel also undertake geophysical studies such as the secular motion of the pole, continental drift, Earth tides and corrections to the fundamental astronomical constants in order to improve the determination and prediction of Earth orientation parameters.

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Last modified: 12 January 2004 Approved by EO Dept. Head, USNO