Comparison of VLBI nutation series with the IAU2000A model
Proceedings of the Journées 2003 "Systèmes de Référence Spatio-Temporels", A. Finkelstein & N. Capitaine (eds.), Institute of Applied Astronomy, St. Petersburg, 24-31 (2004)About the paper Full text
Three most long and dense VLBI nutation series obtained at the Goddard Space Flight Center, Institute of Applied Astronomy, and U. S.Naval Observatory, containing about 3000 estimates of the nutation angles were used for investigation of systemati dierenes between observations and IAU2000A model. Bias and secular trends (precession and obliquity rate) were estimated together with main periodical terms for three periods of observations. It is shown that result substantially depends on period of observations used in analysis. Corrections to some IAU2000A nutation terms were also estimated and found to be at the level up to several tens miroarcseonds. A new Free Core Nutation model with variable amplitude and period (phase) is developed. Comparison of this model with observations shows better agreement than existing one.