THE NUTATION OF A RIGID EARTH MODEL - DIRECT INFLUENCES OF THE PLANETS

This paper presents the nutation of the rigid earth due to the direct influence of the planets, which can reach up to 0.5 milliarcsec (mas) in longitude and 0.2 mas in obliquity. In contrast to the direct computation method of Kinoshita and Souchay [Celest. Mech., 48, 137 (1990)], it is here calculated indirectly via the new planetary tidal potential development recently given by Hartmann and Wenzel [Bull. d'Inform. Marees Terrest., 119, 8847 (1994a)]. The results are (except for two terms) equal within the stated truncation threshold of 0.005 mas. Since we lowered this level to 0.0025 mas, another eleven terms are added. Values for the precession due to the planets are also deduced from the tidal potential.