Revisiting the light time correction in gravimetric missions like GRACE and GRACE follow-on

The gravity field maps of the satellite gravimetry missions GRACE (Gravity Recovery and Climate Experiment) Follow-On are derived by means precise orbit determination. key observation is biased inter-satellite range, which measured primarily a K-Band Ranging system (KBR) in Follow-On. satellites additionally equipped with Laser Interferometer (LRI), provides measurements lower noise compared to KBR. range KBR LRI needs be converted for recovery into an instantaneous i.e. Euclidean distance between satellites' center-of-mass at same time. One contributor difference arises due non-zero travel time electro-magnetic waves spacecraft. We revisit calculation light correction (LTC) from first principles considering general relativistic effects state-of-the-art models Earth's potential field. novel analytical expressions LTC can circumvent numerical limitations classical approach. dependency on geopotential parameterization studied, afterwards results against provided official datasets It shown that new approach has significantly noise, well below instrument current instruments, especially relevant LRI, even if used kinematic products. This allows calculating accurate enough next generation gravimetric missions.