Mitigating Source Structure on the Visibility Level

Source structure is one of the remaining unmodelled systematic errors in geodetic and astrometric VLBI. Our aim is to mitigate the impact of an extended structure at an early point in the processing chain, such that observables appear as if they had been obtained by observation of point sources. We have developed a tool to remove structure phases directly from the DiFX correlator output. Here we describe our method and present results from its application to observational VGOS data.