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Deficiencies in the Model for the Celestial Motion of the Cep as Derived from a Goddard/VLBI Series of Pole Offsets From 1979 to 1989

Published online by Cambridge University Press:  12 April 2016

N. Capitaine  and
B. Caze
N. Capitaine
Affiliation:
Observatoire De Paris - Ura 1125/Cnrs 61, Avenue De L’Observatoire 75014 - ParisFRANCE
B. Caze
Affiliation:
Observatoire De Paris - Ura 1125/Cnrs 61, Avenue De L’Observatoire 75014 - ParisFRANCE

Abstract

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A VLBI series of celestial pole offsets (designated as ERP(GSFC)90 R 01 in the IERS series of Earth Rotation Parameters) spanning 10 years has been used for deriving the corrections to the IAU constant of precession and to the main terms of the 1980 IAU series of nutation using the same method as Herring (1988) for constraining the corrections to the 9.3yr nutation and to the l8.6yr nutation in longitude. The estimated corrections have been found to be − 0.279ʺ/c ± 0.02 ʺ/c (formal error) for the IAU constant of precession and +3.13±0.15mas for the 18.6yr nutation coefficient in obliquity. A circular term with a radius of the order of 0.25mas at a period of 430 days has moreover been revealed in the residuals as obtained after applying the estimated corrections to the series. If such a circular term in the celestial motion of the pole is due to the free core nutation, its estimated period would correspond to a core flattening of 2.687×10−3, which is in good agreement with the one of 2.674×10−3 corresponding to the estimated amplitude of the retrograde annual nutation.

Type
Part 2. Poster Papers
Information
International Astronomical Union Colloquium , Volume 127: Reference Systems , 1991 , pp. 222 - 223
Copyright
Copyright © United States Naval Observatory 1991

References

Capitaine, N. and Caze, B., 1990, ‘Estimation of corrections to the IAU model for the celestial motion of the CEP from VLBI data’, to be submitted to Astron.Astrophys. Google Scholar
Herring, T., 1988, ‘Resolutions to the IAU nutation Working Group’, July 1988.Google Scholar
Kinoshita, H. and Souchay, J., 1990, ‘The theory of the nutation for the rigid Earth model at the second order’, Celest.Mech, in press.Google Scholar