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Read Me documentation for USNO Rapid Products


  • Files available:

    • GPS-satellite orbit + clock files (IGS .sp3 format)

    • GPS-based receiver- and satellite-clock solutions (IGS .clk format)

    • Earth-orientation files (IGS .erp format)

  • Each file provides 24 hours of post-processed solutions.  These files are also available via anonymous ftp at

  • File name convention:

    • usn15002.sp3 provides solutions for GPS week 1500, day 2 (Tuesday), midnight-to-(almost) midnight.

    • Similarly, usn15002.erp, usn15002.clk.

    • general format: usnwwwwd.sp3, .clk, .erp

  • Available ~ 16:00 UTC of following day.


To learn more about these products, click here.

USNO Master Clock Time
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