Comparison between theories of nutation for a rigid-Earth model

The theory of nutation for a rigid-Earth model serves classically as a basis to the theory of nutation for a more elaborate one (including an elastic mantle. a fluid outer core and a solid inner core). In view of the present level of accuracy of the observations new tables of nutation for a rigid-Earth model including all the coefficients up to 0.01 milliarcsec have been determined by (Zhu & Groten 1989) and (Kinoshita & Souchay 1990). We show in detail the dramatic improvement of these two theories with respect to the theory of Kinoshita (1977) as well as a qualitative and quantitative relative comparison.