# IVS EOP Format

##### Version 2.1 (last updated: 2009-01-12)

File names ending with .eops contain nutation offsets in dpsi, deps with respect to the IAU1980 nutation model. File names ending with .eoxy contain nutation offsets in dX and dY with respect to the IAU2006 nutation model (the model should exclude free core nutation).

Files are free format with fields separated by at least one blank.

## Format Notation

FIELD | CONTENTS |
---|---|

1 | MJD of the measurement (with at least 5 decimal digits) |

Earth Orientation | |

2 | x of the pole (arcseconds) |

3 | y of the pole (arcseconds) |

4 | UT1-UTC (seconds) |

Nutation | |

5 | dpsi or dX (milliarcseconds) |

6 | deps or dY (milliarcseconds) |

Uncertainty of Earth Orientation and Nutation | |

7 | uncertainty in x (arcseconds) |

8 | uncertainty in y (arcseconds) |

9 | uncertainty in UT1-UTC (seconds) |

10 | uncertainty in dpsi or dX (milliarcseconds) |

11 | uncertainty in deps or dY (milliarcseconds) |

12 | wrms residual delay of the session in ps (preferably integer) |

Correlations | |

13 | correlation coefficient: x, y |

14 | correlation coefficient: x, UT1 |

15 | correlation coefficient: y, UT1 |

16 | correlation coefficient: dpsi/deps or dX/dY |

Indicators | |

17 | number of observables |

18 | 6 character session code according to the 2nd column of IVS master schedules, e.g for 2017: master18.txt |

19 | span of the observation (in hours) |

Rates of Earth Orientation and Nutation | |

20 | x rate of the pole (arcseconds/day) |

21 | y rate of the pole (arcseconds/day) |

22 | excess length of day (LOD) (seconds), see comment below |

23 | dpsi rate (milliarcseconds/day) |

24 | deps rate (milliarcseconds/day) |

Uncertainty of Rates of Earth Orientation and Nutation | |

25 | uncertainty in x rate (arcseconds/day) |

26 | uncertainty in y rate (arcseconds/day) |

27 | uncertainty in LOD (s) |

28 | uncertainty in dpsi rate (milliarcseconds/day) |

29 | uncertainty in deps rate (milliarcseconds/day) |

Configuration of network employed for these Results | |

30 | sequence of two-character IVS station identifiers as maintained in IVS master control file ns-codes.txt (no blanks between stations) e.g. TsWzWfTcGcFt45Oh, TsWzNy or NyTs N.B.: There may be several lines for an individual session identifying different station configurations |

## Comments

- For the EOP rates, days are in 86400 SI seconds.
- The lines starting with characters "! # or *" are considered as comments.
- Although it is inconsistent to have LOD in the group of rates due to the toggling of the sign, it is maintained here for consistency with other space techniques.

LOD = UT1(n) - UT1(n+1) with n in days. LOD has the same magnitude but opposite sign of the UT1-UTC rate or the UT1-TAI rate, which are normally determined in VLBI analyses and given in seconds/day.