Fitting the Stellar and Planetary Reference Frames: Determination of the Position Differences Between the Catalogue and Dynamical Zero-Points Using Observations of Planets

We discuss the construction of a geometrical model for solving the problem of fitting the catalogue and dynamical zero-points using observations of planets. The equations are derived for determining corrections to catalogue right ascensions and declinations on the basis of this model. The correlation between unknowns are studied, and we have found that the correlation degree of different unknowns varies, depending on the orbit elements of the planet and, as a consequence, unfitted estimates of Delta A and Delta(delta₀) obtained from observations of planets. To illustrate this conclusion, we give the results of zero-point determinations from real observations.