Earth Orientation Center
(Earth Rotation Data)
ICRS Product Center
(Celestial Reference System)

Polar motion for the last years :

Excess of the Length of day for the last years :

Look at their atmospheric excitation

The Paris Observatory is hosting two components of The International Earth Rotation Service: the Earth Orientation and International Celestial Reference Frames Centers, in close association with the International Terrestrial Reference Frame Center, hosted in Institut Géographique National, located in Ile de France. The International Earth Rotation Service (IERS) is an interdisciplinary service that maintains key connections between astronomy, geodesy and geophysics. He provides:

Celestial reference frame

Terrestrial reference frame

Earth orientation data

Permanent information on the Earth fluid layer

IERS Conventions

The service now accomplishes its missions through various components: a Central Bureau, Techniques Centers, Product Centers and Combination Research Centers.