Celestial Pole Offset (CPO) and Free Core Nutation (FCN).
Two regularly updated series are available.
File fcn1.dat contains FCN contribution to CPO
computed making use of model with variable amplitude and phase.
This model is provided for the period from 1984.0 to (current date - 1.5 yr)
to obtain geophysically meaningful data without significant edge effect.
The IVS combined EOP series
is used for computation.
The model is aimed primarily at users who are interested in geophysical
interpretation of the observations.
File fcn2.dat contains CPO series computed by smoothing
the IVS combined EOP series,
and also includes prediction
forward and backward covering the period from 1976 to (last IVS EOP epoch + 2 yr).
This model is aimed primarily at users who need the maximum accuracy of the
CRF<->TRF transformation, including real-time applications, without bothering
about theoretical background and geophysical meaning.
If you use this data in your work, please cite the following paper
Malkin Z.M. Empiric Models of the Earth's Free Core Nutation.
Solar System Research, 2007, v. 41, No. 6, 492-497.
