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Earth Orientation Products

USNO, as the IERS Rapid Service/Prediction Center, provides daily, weekly, and long-term data products.  Data files and plots are categorized into daily, weekly, and long-term products.  The Bulletin A, updated every Thursday, is available here.  An archive of past issues of Bulletin A is here.  If you would like to receive (or unsubscribe from) the Bulletin A electronically, use the document request form.

Daily Solutions

Daily data files available by anonymous ftp.  Updated daily

(normally around 17:05 UTC), for highest accuracy real-time applications.

Weekly Solutions

Standard data files available by anonymous ftp.  Updated weekly

on Thursdays.  Plots of Bulletin A combination and residuals.  Statistical report for contributed series.

Long-term Delta T

Monthly determination of Delta T (TT - UT1) since 1973 and long-term predictions.  Determinations of Delta T are updated approximately quarterly, and long-term predictions from are updated annually.

USNO Master Clock Time
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