Analysis of attitude noise for ITSG GRACE-FO processing

The GRACE/GRACE-FO mission has monitored monthly variations of Earth's gravity field for more than two decades. One source of error is attitude errors, that propagate to inter-satellite range observations through the antenna centre offset correction. This error is proportional to the nominal angle deviation. For GRACE-FO, the third additional camera on-board and the gyroscope made attitude errors negligible. However, with current coarse pointing mode to increase mission lifetime, the propagated attitude errors are enlarged. This work incorporates full covariances for the antenna centre correction to the stochastic model. For this purpose, in-house level-1A attitude data processing is conducted, including sensor fusion from the three star cameras and gyroscope data along with variance component estimation. The impact on the post-fit residuals and the quality of the gravity field recovered are analysed for the solutions of TU Graz Institute of Geodesy.