The free core nutation period stays between 431 and 434 sidereal days
نویسندگان
چکیده
منابع مشابه
Free core nutation observed by VLBI
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 ...
متن کاملA New Free Core Nutation Model with Variable Amplitude and Period
Three most long and dense VLBI nutation series obtained at the Goddard Space Flight Center, Institute of Applied Astronomy, and U.S. Naval Observatory were used for investigation of the Free Core Nutation (FCN) contribution to the celestial pole offset. Some recent studies have showed that the FCN period or/and phase does not remain constant, but varies in a rather wide range of about 410–490 d...
متن کاملEmpiric Models of the Earth’s Free Core Nutation
Free core nutation (FCN) is the main factor that limits the accuracy of the modeling of the motion of Earth’s rotational axis in the celestial coordinate system. Several FCN models have been proposed. A comparative analysis is made of the known models including the model proposed by the author. The use of the FCN model is shown to substantially increase the accuracy of the modeling of Earth’s r...
متن کاملImprovement of Nonrigid - Earth Nutation Theory by Adding a Model Free Core Nutation Term
Abstract. From the analysis of VLBI observational data compiled by USNO (U.S. Naval Observatory) from MJD 44089.994 to 51618.250 (McCarthy, 2000), we showed that a strong peak around 400 sidereal days in the spectrum of its di erences from the IERS96 nutation theory could be explained by adding a model Free Core Nutation (FCN) term in the form of a single damped oscillation. Then we developed a...
متن کاملAn analysis of celestial pole offset observations in the free core nutation frequency band
In this study, three empirical Free Core Nutation (FCN) models developed to the present time, MHB2000, Malkin’s and Lambert’s ones, are compared on the basis of representation of variations of the FCN amplitude and phase predicted by these models. It is possible to conclude, that the model of the author provides the most realistic representation of the FCN variations. However, the specified mod...
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ژورنال
عنوان ژورنال: Geophysical Research Letters
سال: 1999
ISSN: 0094-8276
DOI: 10.1029/1998gl900225