IERS Conventions (2010)

Working Version 1.3.0 — Most Recent

(last updated 1 April 2019)


The official IERS Conventions (2010) was completed on 15 December 2010 as IERS Technical Note 36.
A complete tarball of supporting software and documentation is also available.



Supporting documentation for the Conventions is not part of the official distribution, and is not subject to the same review process.

The Conventions presented in the "Updated" section is a working version that has been modified from the official release of the IERS Conventions (2010). All content in the updated pages should be considered under development and are not definitive nor officially approved as a registered edition. However, the working version does contain all identified corrections to the IERS Conventions (2010).

Some details on the updated pages:
  • If an update has been applied to a given chapter, it will be marked as "(Updated)" next to the chapter name.
  • The latest updates to software and text can be found in the available packaged versions. A list of updates is provided for each chapter on the given chapter page. All updated files are subject to changes in future versions.
  • For all updates to the chapter text:
    1. Changes with respect to IERS Conventions (2010) are denoted with a line in the external margin and a date of when the modification was made.
    2. New sections are identified with a thicker line in the external margin next to their title.

  • Introduction

  • Chapter 1 (Updated)- Definitions and numerical standards
    • 16 November 2017:
      • In Table 1.1, the W0 value has been modified to correspond to the value adopted in the IAG 2015 Resolution (No. 1).

  • Chapter 2- Conventional celestial reference system and frame.

  • Chapter 3- Conventional dynamical realization of the ICRS.

  • Chapter 4 (Updated)- Terrestrial reference systems and frames.
    • 1 April 2019:
      • Chapter 4 has been re-written to accommodate the following updates:
        • A description of ITRF2014, with its associated equations, to model the nonlinear station motions due to seasonal signals and post-seismic deformation of stations subject to major earthquakes.
        • A description of the mathematical model used in the ITRF combination.
        • A revision of Table 4.1, listing the transformation parameters relating ITRF2014 to previous ITRFs.
        • Improvements in wording and the removal of unnecessary paragraphs.

  • Chapter 5 (Updated)- Transformation between the International Terrestrial Reference System and Geocentric Celestial Reference System
    • 21 December 2013:
      • Report the yearly update fcnnut130701 to the Free Core Nutation model
    • 10 August 2012: Changes with respect to previous version of the chapter:
      • Report the yearly update fcnnut120701 to the Free Core Nutation model and correct a typo in the value of the FCN period.
    • 14 October 2011:
      • The header of the subroutine PMSDNUT2.F has been corrected to point to the correct section of Chapter 5 and to provide a new test case.
    • 13 July 2011: Main changes with respect to previous version of the chapter:
      • Correct Tables 5.3a and 5.3b: Column headers misplaced in the "paper" version; One typo in the electronic version.
      • Report an error in the version of Table 5.3b that was published with the Conventions (2003).
      • Correct in Table 5.2f the formula for the polynomial part of Y_IAU 2006 - Y_IAU 2000A.
      • Clarify the text describing the implementation of the IAU 2000A nutation model by the SOFA (Software of Fundamental Astronomy) service.
      • Report the yearly update fcnnut110701 to the Free Core Nutation model.
      • Correct several typos or improper wordings.

  • Chapter 6 (Updated)- Geopotential
    • 1 February 2018:
      • Reference to mean pole has been replaced with mean figure axis.
      • Other minor changes to the text in Section 6.1.
    • 10 August 2012:
      Changes with respect to previous version of the chapter:
      • A clarification has been added to section 6.3.2 "Ocean tide models", part "FES2004", specifying how the zonal terms should be treated to consistently obtain Stokes coefficients.
    • 14 October 2011:
      Main changes with respect to previous version of the chapter:
      • Corrected errors in fes2004_Cnm-Snm.dat: Coefficients for the waves Sa and P1 were computed with an erroneous phase.
      • In the section 6.3.2 "Ocean tide models", part "FES2004", there is an ongoing discussion on the phase of the C20 term of the very long period waves (pi/2 as per the update of 23 September 2011 or -pi/2). A warning sentence has been inserted in the text. The same warning applies to the values in the first two data lines of the files fes2004.dat and fes2004_Cnm-Snm.dat, which remain as in the update of 23 September 2011.
    • 23 September 2011:
      Main changes with respect to previous version of the chapter:
      • Corrected an error in the file fes2004_Cnm-Snm.dat: The unit of coefficients is 10^-11.
      • In the section 6.3.2 "Ocean tide models", part "FES2004", the phase of the C20 term of the very long period waves has been corrected to pi/2.[1] The corresponding changes are introduced in the first two data lines of the files fes2004.dat and fes2004_Cnm-Snm.dat.

  • Chapter 7 (Updated)- Displacement of reference points
    • 28 December 2018:
      • Subroutine IERS_CMP_2015.F has been removed, as the Conventional Mean Pole is no longer supported by the IERS Conventions. This brings the software into alignment with the Chapter 7 text.
    • 1 February 2018:
      • Section 7.1.4 has been rewritten to include the secular pole and remove the former mean pole.
    • 31 March 2017:
      • In Section 7.1.4 (pg. 16) of chapter text, the last point of observed mean pole values has been corrected to read "epoch (YYYY-1).0". It had been previously written as "YYYY.0".
    • 20 December 2016:
      • To account of the leap second occurring on 31 December 2016:
      • Other Changes:
        • An updated CAL2JD.F, a subroutine of DEHANTTIDEINEL.F, was added from the 12th release of the SOFA package.
    • 19 June 2015:
      • The program HARDISP.F, its subroutine ETUTC.F, the subroutine DEHANTTIDEINEL.F and its subroutine from the SOFA package, DAT.F were updated to account of the leap second occurring on 30 June 2015.
      • Corrected Errors:
        • Two subroutines of the HARDISP.F package have been corrected for bugs and the test cases of all affected routines have been subsequently modified and completed. The potential error on the HARDISP results is less than 0.1 mm.
          1. Two variables in ETUTC.F have been changed from single to double precision
          2. Error in number of seconds/day in the subroutine TDFRPH.F has been corrected. A new test case utilizing non-zero time has been added.
        • The test case has been modified in HARDISP.F to utilize non-zero time and correct for the change to double precision in ETUTC.F
        • Previously missing data in the test run of the ocean pole tide model was added. An explanatory sentence has been added to section 7.1.5, "Ocean pole tide loading."
        • Typos present in the text of the Conventions (2010), have been corrected in the paragraph following Table 7.1 and in Section 7.1.5.
      • Other changes:
        • A new version of the IERS Conventional Mean Pole (CMP) is realized in the IERS subroutine, IERS_CMP_2015.F. See Section 7.1.4, "Rotational deformation due to polar motion" for more information. The CMP change also affects the computation of the pole tide effects on the geopotential, see Chapter 6 (Updated).
        • An updated CAL2JD.F, a subroutine of DEHANTTIDEINEL.F, was added from the 11th release of the SOFA package.
    • 10 June 2013:
      • The subroutine DEHANTTIDEINEL.F is corrected for a bug that occurred at the update dated 26 March 2012. [2] The potential error is below 0.1 mm.
      • 24 Dec 2013: The subroutine TDFRPH.F used in the HARDISP package is corrected for an error in the test case. Also, the subroutine TDFRPH2.F has been removed as it was not used.
    • 26 March 2012:
      The following have been modified to account for the 30 June 2012 leap second:
      • The program HARDISP.F, its subroutine ETUTC.F, the subroutine DEHANTTIDEINEL.F and its subroutines from the SOFA package DAT.F and CAL2JD.F have been modified to account for the next leap second to occur 30 June 2012.
      • An updated CAL2JD.F, a subroutine of DEHANTTIDEINEL.F, was added from the latest SOFA package. Note that the previous version of DEHANTTIDEINEL.F erroneously did not include the update dated 10 April 2009. This version reinstalls this update (a 0.05 mm effect).
    • 14 October 2011:
      • The subroutine ARG2.F has been corrected to not modify internally the IYEAR argument (the four-digit year).
    • 23 September 2011:
      • The subroutine ARG2.F has been corrected for a bug that caused an error for dates starting with year 2000. [1] Note that the IYEAR argument is now the four-digit year.

  • Chapter 8 (Updated)- Tidal variations in Earth's rotation
    • 22 December 2011:
      • The subroutine RG_ZONT2.F has been corrected for a typo in the sine coefficient of the 365.26 day period for delta LOD.[1] The effect is of the order of a ns over the length of a day.

  • Chapter 9 (Updated)- Models for atmospheric propagation delays
    • 10 June 2013:
      • The subroutine GPT2.F has been updated for consistency with the version at TU Wien. This version ensures proper function at the South pole [1], and the parameter "dmjd" is no longer modified by the subroutine [2]. A reference has been added in the Chapter 9 text.
    • 15 January 2013:
      • Introduce the model Global Pressure and Temperature 2 in sections 9.2 "Tropospheric model for radio techniques" and 9.3 "Sources for meteorological data". [3]
      • In the section 9.4 "Ionospheric models for radio techniques", correct some numerical values in a number of equations for using exact CODATA (2010) values of fundamental constants.[4] Changes are not significant with respect to the uncertainties of the quantities.
    • 10 August 2012:
      Changes with respect to previous version of the chapter:
      • In the section 9.2 "Tropospheric model for radio techniques", correct a typo in the Chen and Herring gradient mapping function.
      • In the section 9.4.1 "Ionospheric delay dependence on radio signals including higher order terms", the part "Ray bending effects on geometric path excess and ionospheric delay" has been updated.[5]
    • 26 March 2012:
      • The test case provided for the subroutine VMF1.F has been corrected. The subroutine VMF1_HT.F has been corrected for an error in the computation of the quantity VMF1H [6] and for the test case.
    • 25 November 2011:
      • The header of the subroutine GPT.F has been corrected for the test case output. [7]

  • Chapter 10- General relativistic models for space-time coordinates and equations of motion.

  • Chapter 11- General relativistic models for propagation.

  • Appendices (Updated)
    • 15 January 2013:
      • Addition of Appendix E for the IUGG Resolution 3 Adopted at the XXVth General Assembly (2012).

  • Glossary (Updated)
    • 28 December 2018:
      • Modify definition of "mean pole" and "polar motion".
      • Introduce definition for "secular pole".
    • 22 December 2011:
      • In the term "celestial pole offsets," replace "IAU 2000" with "IAU 2006/2000".