In the process of using Orekit, I employed the LevenbergMarquardtOptimizer optimizer, the KeplerianPropagatorBuilder propagator, and the BatchLSEstimator estimator for orbit determination. I input the initial orbit’s six classical orbital elements, where the true anomaly was set to 360° and the inclination to 55°. I also provided existing observation data (time T, range R, azimuth A, elevation E). However, the resulting refined orbit showed an inclination of 66°. Under normal circumstances, without any maneuvers, the inclination should not change significantly.
However, when using the same observation data, I adjusted the initial true anomaly to any angle between 20° and 60°, and the final refined orbit’s inclination varied only slightly around 55°. Why is this happening?