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International Earth Rotation and Reference Systems Service

Data / Products / Tools

The IERS provides data on Earth orientation, on the International Celestial Reference System/Frame, on the International Terrestrial Reference System/Frame, and on geophysical fluids. It maintains also Conventions containing models, constants and standards.

For regular information on changes concerning IERS data, products and tools please register as IERS user and subscribe to IERS Messages.

Earth orientation data

IERS provides rapid, monthly and long term earth orientation data as well as leap second announcements and announcements of DUT1 in the form of bulletins or data files.



The International Celestial Reference Frame (ICRF) consists of equatorial coordinates of extragalactic radio sources observed with VLBI, realizing an ideal reference system, the International Celestial Reference System (ICRS).



The International Terrestrial Reference Frame (ITRF) is a set of points with their 3-dimensional cartesian coordinates which realize an ideal reference system, the International Terrestrial Reference System (ITRS).


Geophysical fluids data

Global geophysical fluids data provide information related to Earth rotation variation, gravity field variation and geocenter motion that are caused by mass transports in the global geophysical fluids (atmosphere, oceans, hydrology, tides, mantle, core).


IERS Conventions

The IERS Conventions define the standard reference system to be used by the IERS. They contain conventional models, constants and standards.


Data analysis tools

For visualization and analysis of IERS data and products several tools are available.


The IERS issues also Annual Reports, Technical Notes and other publications. The content of the product descriptions are based on the results of a survey on the IERS products performed by the IERS Analysis Coordinator.