Abstract: Two ways of defining the Poincaré astrocentric coordinates in the planetary problem are considered and compared. Both ways are shown to lead to the same system of equations of planetary motion after the elimination of the center of mass. Formulas for the transition from the osculating elements in the Poincaré coordinate system to the ordinary astrocentric osculating elements are given. The analytical apparatus constructed here is suitable for the practical application of perturbation methods, in particular, averaging methods.