Determination of FCN parameters from different VLBI solutions, considering geophysical excitations

0539560 - ASÚ 2022 FR eng C - Conference Paper (international conference)
Vondrák, Jan - Ron, Cyril
Determination of FCN parameters from different VLBI solutions, considering geophysical excitations.
Proceedings of the Journées 2019: Astrometry, Earth Rotation, and Reference Systems in the GAIA era. Paris: Observatoire de Paris, 2020 - (Bizouard, C.), s. 255-259
[Proceedings of the Journées 2019: Astrometry, Earth Rotation, and Reference Systems in the GAIA era. Paris (FR), 07.10.2019-09.10.2019]
Institutional support: RVO:67985815
Keywords : free core nutation * geophysical excitations * VLBI observations
OECD category: Astronomy (including astrophysics,space science)
https://syrte.obspm.fr/astro/journees2019/LATEX/JOURNEES2019.pdf

Different VLBI solutions of celestial pole offsets (CPO) are used to determine parameters (period T and Q-factor) of Free Core Nutation (FCN). To this end, Brzezinski's broad-band Liouville equations are numerically integrated to account for geophysical excitations. Effects of the atmosphere, oceans and geomagnetic jerks (GMJ) are considered. Best-fitting values of FCN parameters are found by least-squares fit to observed CPO, corrected for the difference between the FCN parameters used in IAU 2000 model of nutation and newly estimated ones, MHB transfer function is used to compute these corrections. Out of all 42 solutions that we made the best fit is obtained for CPO from IERS C04, with only GMJ excitations considered. Estimated values of FCN parameters from this solution are T=430.23±0.03, Q=19600±130. Very probably, excitations of FCN by GMJ are more important than those by the atmosphere and oceans.
Permanent Link: http://hdl.handle.net/11104/0317278