Astron. Astrophys. 318, 639-652 (1997)

1. Introduction

The dramatic improvement of the accuracy of the VLBI observations in the last decade leads to some estimations of the coefficients of the nutation of the Earth at a few microarcseconds accuracy. Thus it became necessary to be confident in the values of the coefficients of the nutation of the Earth for a simplified rigid model, at less at the microarcsecond level. In the present paper we check the analytically determined coefficients of the nutation for a rigid Earth model as calculated by Kinoshita & Souchay (1990), due to small influences of the potential of the Earth (, , , ), and to the direct torque exerted by the planets (also quoted as the direct planetary effect) up to their level of truncation, that is to say 5 microarcseconds. Moreover we calculate also the coefficients ranging between 0.1 microarcseconds and 5 microarcseconds, in order to perform a comparison with recent calculations done by Hartmann et al. (1995) and Williams (1995), respectively for the two kinds of effects above.

© European Southern Observatory (ESO) 1997

Online publication: July 8, 1998
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