The determination of Earth orientation by VLBI and GNSS: principles and results

Capitaine, Nicole

The Earth orientation parameters (EOP) connect the International Terrestrial Reference System (ITRS) to the International Celestial Reference System (ICRS). These parameters, i.e. Universal Time, UT1, and pole coordinates in the ITRS and the GCRS, describe the irregularities of the Earth's rotation. They are mainly determined by two modern astro-geodetic techniques, VLBI (Very Long Baseline Radio Interferomety) on extragalactic radio sources, which is used to realize and maintain the ICRS, and Global Navigation Satellite Systems (GNSS), which has an important contribution to the realization of the ITRS.

The aim of this presentation is to discuss how the principles of the two techniques, which are VLBI and GPS, give access to the measure of the different components of the variations in EOP, especially UT1. The accuracy that can be achieved is based on the improved concepts, definitions and models that have been adopted by the IAU resolutions on reference systems, as well as on the refined strategy of the observations.

Return to invited speaker list