Gravity Field Determination at the AIUB - The Celestial Mechanics Approach

We present the gravity field model AIUB-CHAMP01S, which has been generated using the Celestial Mechanics approach. GPS-derived kinematic positions of low Earth orbiters (LEOs) are used as pseudo-observations to solve for the Earth's gravity field parameters in a generalized orbit determination problem. Apart from normalized spherical harmonic (SH) coefficients, arc-specific parameters (e.g., accelerometer calibration parameters, dynamical parameters, or pseudo-stochastic parameters) are set up and normal equations are written for all daily LEO arcs. The daily normal equations are combined to weekly, monthly, and annual systems before inversion. The parametrization can be modified on the normal equation level without a new time-consuming set up of the daily normal equations. The results based on one year of CHAMP data demonstrate that the Celestial Mechanics approach is comparable in quality with other approaches.