Analysis of Satellite Laser Ranging Observations

DGFI-TUM has a broad expertise in the analysis of laser ranging observations to satellites (SLR). In the framework of the International Laser Ranging Service (ILRS), DGFI-TUM acts as an official analysis center (AC) and is in charge with the analysis, quality assessment, bias determination and quick look data validation of laser ranging measurements performed by globally distributed stations. For this purpose, DGFI-TUM developed a software package called 'DGFI Orbit and Geodetic parameter estimation Software' (DOGS) which consists of several libraries for the integration of satellite orbits based on laser observations, the simulation of laser observations and the estimation of geodetic parameters. Besides the operational use of the software, it is further developed in order to improve the accuracy of geodetic parameter estimates, incorporate new target quantities and enlarge its functionality to, e.g., other geodetic observation techniques. In addition to the observation analysis, DGFI-TUM operates the EUROLAS data center which is one of two global archives for laser ranging observations.

The applications of laser ranging observations are manifold. Besides the determination of station coordinates and Earth Orientation Parameters (EOP), SLRcan be also used to determine coefficients of the Earth's gravity field, thermospheric parameters and relativistic quantities. A special role plays SLR for the realization of the International Terrestrial Reference System (ITRS) since its origin is defined to coincide with the Earth's center of mass. Precise laser ranging measurements to spherical satellites (reduced impact of non-conservative perturbations) allow to determine the Earth's center of mass with very high accuracy and are therefore used to realize the ITRS realization origin.