Earth Orientation Parameters Data Documentation

  • Data used:

    1. Files:

      Contains: NGA coefficients for the upcoming week (see Documentation)

      Updated: Daily
      Each day a file of the form EOPPyddd.TXT is produced where y is the last digit of the year and ddd is the day of the year.

    2. Files:

      Contains: Observed data (x, y, UT1-UTC, LOD, δΔψ, δΔε), (δX, δY)

      Updated: Daily

    3. Files:

      Contains: TAI-UTC data

      Updated: With new leap seconds

  • Data documentation can be found at:

  • Process:

    1. NGA coefficients for the coming week are obtained from Source 1.

    2. Observed data is obtained from Source 2.

    3. Predicted data is also obtained from Source 2 and goes out 180 days.

    4. Delta Atomic Time (TAI-UTC)/leap second data is obtained from Source 3.

  • Keywords:

    • VERSION major.minor
      Provides major and minor version of current data format.

    • UPDATED yyyy Mon dd hh:mm:ss UTC
      Provides UTC date and time of current update.

    • BEGIN NGA_COEFFICIENTS
      END NGA_COEFFICIENTS
      Marks beginning and end of NGA coefficients.

    • NUM_OBSERVED_POINTS number
      Indicates number of records of data in the Observed Data section.

    • BEGIN OBSERVED
      END OBSERVED
      Marks beginning and end of the Observed Data section.

    • NUM_PREDICTED_POINTS number
      Indicates number of records of data in the Predicted Data section.

    • BEGIN PREDICTED
      END PREDICTED
      Marks beginning and end of the Predicted Data section.

  • Observed and Predicted Data Format:

    ------------------------------------------------------------------------------------------------------
    FORMAT(I4,I3,I3,I6,2F10.6,2F11.7,4F10.6,I4)
    ------------------------------------------------------------------------------------------------------
    Column
    000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000111
    000000000111111111122222222223333333333444444444455555555556666666666777777777788888888889999999999000
    123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012
    ------------------------------------------------------------------------------------------------------
    yyyy dd mm MJD      x         y        UT1-UTC     LOD        dPsi    dEpsilon    dX        dY     DAT
    ------------------------------------------------------------------------------------------------------
    yyyy dd mm nnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnnn +n.nnnnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnn nnn
    ------------------------------------------------------------------------------------------------------
    2000 01 01 51544  0.043251  0.377681  0.3555151  0.0009068 -0.050825 -0.002257 -0.000222  0.000124  32
    ------------------------------------------------------------------------------------------------------
    
    ColumnsDescription
    001-004Year
    006-007Month (01-12)
    009-010Day
    012-016Modified Julian Date (Julian Date at 0h UT minus 2400000.5)
    018-026x (arc seconds)
    028-036y (arc seconds)
    038-047UT1-UTC (seconds)
    049-058Length of Day (seconds)
    060-068δΔψ (arc seconds)
    070-078δΔε (arc seconds)
    080-088δX (arc seconds)
    090-098δY (arc seconds)
    100-102Delta Atomic Time, TAI-UTC (seconds)

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Dr. T.S. Kelso [TS.Kelso@celestrak.com]
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Last updated: 2018 Jul 02 20:26:32 UTC
Accessed 96,115 times since 2000 December 16
Current system time: 2019 Oct 15 18:06:58 UTC