On the possibility of using VLBI phase referencing to observe GNSS satellites

The phase referencing technique is an ob- serving method that could contribute to improve ac- curacy in GNSS satellite positioning and to obtain satellite coordinates directly in ICRF. However, the strong power emitted by the satellites compared to the very low emission of natural radio sources (calibrators) could represent a limiting factor. In fact, the satellite signal can be easily detected through near sidelobes when observing, at the same satellite frequency, the natural calibrator in the main beam. With this work we have run some simulations for some European VLBI antennas using the GRASP (General Reflector antenna Analysis Software Package) v.10 software to assess the relative power contribution of satellites in the near sidelobes when observing in L-band a natural calibra- tor in the main beam. For each examined station, we have evaluated the minimum angular distance between the satellite and the calibrator to avoid near-sidelobes straylight contamination from the satellite emission when the calibrator is tracked. A discussion of the ob- tained results is presented and possible observational methods are suggested.