[G01-2] Celestial reference frame and VLBI

[G01-2-02] Testing of special relativity with geodetic VLBI

^○Oleg Titov¹, Hana Krasna² (1.Geoscience Australia, Canberra, Australia, 2.TU Wien, Vienna, Austria)

The geodetic Very Long Baseline Interferometry (VLBI) measures the group delay observable in the barycentric reference frame. As the Earth is orbiting around the Solar System Barycentre with the velocity V of 30 km/s,the VLBI turns to be a handy tool to detect the subtle effects of the special relativity theory with a magnitude of (V/c)^2. The theoretical correction for the second order terms reaches up to 300 ps, and it is implemented in the geodetic VLBI group delay model. The total contribution of the second order terms splits to two effects - the contraction of the Earth scale in the plane perpendicular to the orbital velocity vector direction, and the displacement of the radio source apparent position. We are using the Robertson-Mansouri-Sexl (RMS) formalism to probe the Lorentz invariance. We analyse the geodetic VLBI data with two independent software packages (OCCAM and VieVS) and show that the parameters of the RMS model can be estimated with a high accuracy.