International Earth Rotation Service

Project Description
The International Earth Rotation Service (IERS) is an
interdisciplinary service that maintains key connections between
astronomy, geodesy and geophysics. Her provides:

-Celestial reference frame
-Terrestrial reference frame
-Earth orientation data
-Permanent information on the Earth fluid layer
-IERS Conventions

For more information, link to http://hpiers.obspm.fr/