| Issue |
A&A
Volume 555, July 2013
|
|
|---|---|---|
| Article Number | A29 | |
| Number of page(s) | 5 | |
| Section | Celestial mechanics and astrometry | |
| DOI | https://doi.org/10.1051/0004-6361/201321585 | |
| Published online | 24 June 2013 | |
Free core nutation observed by VLBI
1
Vienna University of TechnologyDepartment of Geodesy and
Geoinformation, Research Group Advanced Geodesy,
Gusshausstrasse
27–29,
1040
Vienna,
Austria
e-mail:
hana.krasna@tuwien.ac.at
2
Helmholtz-Zentrum Potsdam, DeutschesGeoForschungsZentrum GFZ,
Department 1: Geodesy and Remote Sensing, Potsdam, Germany
Received:
27
March
2013
Accepted:
24
April
2013
Aims. The signature of free core nutation (FCN) is found in the motion of the celestial intermediate pole in the celestial reference frame and in the resonance behaviour of the frequency-dependent Earth tidal displacement in its diurnal band. We focus on estimation of the FCN parameters, i.e. the period and amplitude.
Methods. We run several global adjustments of 27 years of very long baseline interferometry (VLBI) data (1984.0–2011.0) to determine the FCN period from partial derivatives of the VLBI observables with respect to the FCN as contained in the nutation of the celestial intermediate pole and in the solid Earth tidal displacement in the diurnal band. Finally, we estimate the FCN period by a global adjustment from both phenomena simultaneously, which has not been done before.
Results. We find that our estimate of the FCN period of −431.18 ± 0.10 sidereal days slightly deviates from the conventional value of −431.39 sidereal days. Additionally, we present our empirical model of the FCN with variable amplitude and phase compatible with the estimated period.
Key words: publications, bibliography / methods: data analysis / techniques: interferometric / astrometry / reference systems / Earth
© ESO, 2013
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