The geophysical approach towards the nutation of a rigid Earth

¹ Theoretische Astrophysik der Universität Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen, Germany
² Institut für Planetare Geodäsie, Lohrmann Observatorium, Mommsenstraße 13, D-01062 Dresden, Germany

Send offprint request to: M. Soffel

Received: 21 January 1998
Accepted: 12 August 1998

Abstract

This paper presents the new and complete series named H96NUT for the nutation of a rigid Earth model. In contrast to the traditional computation method, the nutation is calculated here indirectly via the new and highly accurate tidal potential development recently given Hartmann & Wenzel (1995a,b), (HW95). All contributions up to 0.45 μas were taken into account leading to 699 nutation terms separated after origin (or 607 terms summed according to the same arguments). These are: the main terms due to the Moon, the Sun and the planets, indirect planetary effects, effects due to the triaxiality of the Earth, effects due to the J₃ and J₄ geopotential, the geodesic nutation and second order terms. Nutation series for the angular momentum axis, the figure axis and the rotation axis are derived; they are in good agreement with those given in Roosbeek & Dehant (1997) with exception of several terms whose cause is discussed. Modern constants (like the precession constant) have been used throughout. The value for the dynamical ellipticity H_dyn, which is compatible with these computations, is . In addition, some other values related with precession are also deduced from the tidal potential. One main advantage of this work is that a completely independent analytical computation method has been established which is extensively described here (see also Hartmann for more details) and which provides – besides a numerical calculation – a useful validation of existing nutation series.