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 کاملFree core nutation resonance parameters from VLBI and superconducting gravimeter data
Context. The free core nutation (FCN) can be observed by its associated resonance effects on the forced nutations of the Earth’s figure axis, as observed by very long baseline interferometry (VLBI), or on the diurnal tidal waves, retrieved from the time-varying surface gravity recorded by superconducting gravimeters (SG). Aims. In this paper, we study the sensitivity of both techniques to the F...
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 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 کاملQuasar Apparent Proper Motion Observed by Geodetic VLBI Networks
In our standard geodetic VLBI solutions, we estimate the positions of quasars assuming that their positions do not vary in time. However, in solutions estimating proper motion, a significant number of quasars show apparent proper motion greater than 50 μas/yr. For individual quasars, there are source structure effects that cause apparent proper motion. To examine how coherent the pattern of app...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2013
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/201321585