HIPPARCOS MINOR PLANETS - FIRST STEP TOWARDS THE LINK BETWEEN THE HIPPARCOS AND THE DYNAMICAL REFERENCE FRAMES

The observations of minor planets are of particular interest for deter mining a possible rotation between the Hipparcos and the dynamical ref erence frames. In order to evaluate these unknowns, Hipparcos data are compared to the values calculated from the equations of motion. The s atellite's observations are related to intermediate reference frames c alled Reference Great Circle (RGC). In the case of a minor planet only the abscissa along a given RGC can be observed. The associated equati ons of condition involve in addition the orbital elements and dynamica l parameters (such as masses of minor planets, etc.). For the minor pl anets, the accuracy of the satellite observations is quite better than the ground-based one. So, an improved determination of the unknowns u nder study can be expected. In this paper, the problem of the stabilit y of a classical least squares solution is studied. Due to correlation s, the system of normal equations is highly ill-conditioned. A statist ical methodology is being constructed for a better determination of th e parameters of interest. It is tested on the preliminary Hipparcos da ta. Singular value analysis and principal components regression are pe rformed.