Welcome to the IERS Conventions website

The primary product of the Center is the IERS Conventions. The IERS Conventions describes the reference systems realized by the IERS, in addition to developing and maintaining the models and procedures used to support this endeavor.


The Conventions are in book-form, published on our website and the IERS website as a PDF. Updated versions are published every several years when a sufficient volume of material requires updating. The latest version is the IERS Conventions (2010), published as Technical Note 36. It can also be downloaded on our website in full, or by chapter.


  • Updates to the most recent Conventions are available through the "Conventions>Conventions Updates" drop-down menu above.

  • The same information can be found at both the Obervatoire de Paris and U.S. Naval Observatory Conventions websites.

  • We also provide Additional material that has been developed by individuals to support the Conventions.

  • Our FTP site contains a complete set of files and associated software.