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IERS Message No. 74                                        July 14, 2005
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 Earth Orientation Parameters Prediction Comparison Campaign (EOP PCC)

                        Call for participation


The Institute of Geodesy and Geophysics of the Vienna University of 
Technology invites you to participate in the Earth Orientation 
Parameters Prediction Comparison Campaign (EOP PCC) in an effort to 
determine the current state of the art in Earth Orientation Parameter 
(EOP) predictions. 

Nowadays, the precise relationship between the celestial (ICRF) and 
terrestrial reference frame (ITRF) is needed to perform many advanced 
geodetic and astronomical tasks. For this transformation the EOP derived
from VLBI, SLR, GPS, DORIS observations are used. For some tasks also 
real-time and even future EOP data are needed. Within the IERS 
operational predictions are provided by the IERS Rapid Service / 
Prediction Centre (RS / PC) at United States Naval Observatory (USNO). 
The main idea of this campaign is to compare the various methods, 
models, techniques and strategies that can be applied to EOP prediction.
Each time series will be treated by the same statistical methods and – 
what is different to many previous studies – the predictions have to be
submitted before any EOP observations are taken in order to match the 
conditions under which predictions are made. We think it is an excellent
opportunity to present your experience and work in the field of 
prediction techniques as well as a great possibility to compare the 
results with the same fixed conditions. 

There will be three categories of prediction (ultra short-term, 
short-term and medium-term). Participants are invited to submit 
prediction results for any of the EOP: the xp, yp pole coordinates, 
UT1-UTC differences between Earth rotation time and clock time, length 
of day (LOD), and dX, dY (or dPsi, dEpsilon) celestial pole offsets. 

Currently, the largest errors in the EOPs are found in the prediction of
UT1-UTC and polar motion.  From a practical perspective, the EOP PCC 
would especially like to encourage efforts that would improve 
predictions in these areas.  Also, since the IAU2000A model has been 
adopted recently, much of modelling nutation is well understood.  To 
complement the current situation, the EOP PCC would like to encourage 
those interested in predicting nutation to concentrate on the areas not 
covered in the IAU2000A model (i.e. variable annual motion and the free 
core nutation).  To that end, the EOP PCC will restrict the comparison 
of celestial pole offsets to medium-term predictions only.

If you are interested to participate in the Earth Orientation Parameters
Prediction Comparison Campaign (EOP PCC) you will find more detailed 
information at 

    http://www.iers.org/iers/about/campaigns/eop-pcc/CfP_EOP_PCC.pdf


On behalf of Professor Harald Schuh
Technical University Vienna, Austria

Bernd Richter
IERS Centralbureau
<central_bureau@iers.org>


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