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The free core nutation period stays between 431 and 434 sidereal days
Author(s) -
Roosbeek F.,
Defraigne P.,
Feissel M.,
Dehant V.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900225
Subject(s) - sidereal time , nutation , very long baseline interferometry , core (optical fiber) , geodesy , precession , secular variation , period (music) , noise (video) , physics , geology , astrophysics , astronomy , computer science , optics , artificial intelligence , acoustics , image (mathematics)
We determine the parameters of the Free Core Nutation ( FCN ) from the resonance induced in the forced nutations by a least‐squares analysis of VLBI observations. By applying the procedure to consecutive observation series, we deduce the time evolution of the FCN period, and show that it varies only between 431 and 434 sidereal days. These bounds are within the limits of uncertainty arising from noise in the data. We therefore find no evidence for time variation of the FCN period.