Comparison of the representations of the motions of the eight major satellites of Saturn.

Duriez L., Vienne A.

Universite de Lille, France

A new theory of motion of Hyperion, fitted to observations and put in the same formalism and reference frame as TASS1.6 (Astron. Astrophys 1995, 297, 588-605) is now included in TASS. That represents a global and consistent theory whose adjusted parameters are the masses, the oblateness coefficients of Saturn and the initial conditions of each satellite. The internal precision of TASS over 100 years is between 10 km for Rhea and 250 km for Hyperion. The comparisons to observations and to the other theories (Dourneau (1993), Harper and Taylor (1993)), show that in spite of intrinsic differences between TASS and these theories, the rms residuals with observations are somewhat equivalent (between 0"12 for Rhea and 0"22 for Hyperion), giving in fact the real precision of the available terrestrial observations, and not the precision of the theories.