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 second information from Bulletin C 61 at the Observatoire de Paris
Data documentation can be found at:
- Earth Orientation Parameter Prediction Description (NGA Coefficients)
- EOP C04 Series
- Explanatory Supplement to IERS Bulletins A and B
Process:
1. NGA coefficients for the coming week are obtained from Source 1 (legacy format only).
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.

CSV Data Format:

DATE,MJD,X,Y,UT1-UTC,LOD,DPSI,DEPS,DX,DY,DAT,DATA_TYPE
2000-01-01,51544,0.043282,0.377909,0.3553880,0.0009536,-0.050263,-0.002471,-0.000005,-0.000050,32,O

Field	Description
DATE	UTC Year-Month-Day (ISO 8601)
MJD	Modified Julian Date (Julian Date at 0h UTC minus 2400000.5)
X	x (arc seconds)
Y	y (arc seconds)
UT1-UTC	UT1-UTC (seconds)
LOD	Length of Day (seconds)
DPSI	δΔψ (arc seconds)
DEPS	δΔε (arc seconds)
DX	δX (arc seconds)
DY	δY (arc seconds)
DAT	Delta Atomic Time, TAI-UTC (seconds)
DATA_TYPE	O = Observed, P = Predicted

Legacy Data Format:

------------------------------------------------------------------------------------------------------
FORMAT(I4,I3,I3,I6,2F10.6,2F11.7,4F10.6,I4)
------------------------------------------------------------------------------------------------------
Column
000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000111
000000000111111111122222222223333333333444444444455555555556666666666777777777788888888889999999999000
123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012
------------------------------------------------------------------------------------------------------
    Date    MJD      x         y       UT1-UTC      LOD       dPsi    dEpsilon     dX        dY    DAT
  (0h UTC)           "         "          s          s          "        "          "         "     s 
------------------------------------------------------------------------------------------------------
yyyy mm dd nnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnnn +n.nnnnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnn +n.nnnnnn nnn
------------------------------------------------------------------------------------------------------
2000 01 01 51544  0.043282  0.377909  0.3553880  0.0009536 -0.050263 -0.002471 -0.000005 -0.000050  32
------------------------------------------------------------------------------------------------------

Columns	Description
001-004	Year
006-007	Month (01-12)
009-010	Day
012-016	Modified Julian Date (Julian Date at 0h UTC minus 2400000.5)
018-026	x (arc seconds)
028-036	y (arc seconds)
038-047	UT1-UTC (seconds)
049-058	Length of Day (seconds)
060-068	δΔψ (arc seconds)
070-078	δΔε (arc seconds)
080-088	δX (arc seconds)
090-098	δY (arc seconds)
100-102	Delta Atomic Time, TAI-UTC (seconds)

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.