The solid Earth tide model as recommended by the IERS standards [McCarthy, 1992> and used in standard Very Long Baseline Interferometry [VLBI> data analysis only approximates to the first order the frequency dependence of the tidal deformation due to the Free Core Nutation [FCN> resonance. It is shown that frequency dependent second degree Love and Shida numbers have to be taken into account if the tidal displacements are to be modeled to better than ¿5 mm. We also determined second degree Love and Shida numbers for different tidal bands (long-period, diurnal, semidiurnal) and third degree Love and Shida numbers from VLBI data. The results for the different parts of the tidal spectrum are slightly different and a clear resonance can be seen around the FCN. The FCN period was determined to 426¿20 sidereal days in the celestial reference frame. ¿ American Geophysical Union 1996 |