Determination of the relativistic parameter gamma using very long baseline interferometry

Understand

Relativistic bending in the vicinity of a massive body is characterized only by the post-Newtonian parameter $\gamma$ within the standard parameterized post-Newtonian formalism, which is unity in General Relativity.

• Aiming at estimating this parameter, we use very long baseline interferometry (VLBI) to measure the gravitational deflection of radio waves emitted by distant compact radio sources, by Solar System bodies.
• We analyze geodetic VLBI observations recorded since 1979.
• We compare estimates of $\gamma$ and errors obtained using various analysis schemes including global estimations over several time spans and with various Sun elongation cut-off angles, and analysis of radio source coordinate time series.