MultiView phase corrections at low frequencies for precise astrometry

TL;DR

This paper introduces MultiView, a multi-calibrator solution for low-frequency VLBI astrometry, demonstrating improved accuracy over traditional methods by effectively mitigating ionospheric residuals.

Contribution

The paper presents a novel MultiView technique for precise low-frequency astrometry and a new method to detect antenna systematic errors, validated with VLBA observations.

Findings

MultiView achieves astrometric accuracy at the thermal noise level.

MultiView outperforms conventional phase referencing techniques.

A new method detects antenna systematic errors effectively.

Abstract

We present a multi-calibrator solution, i.e. MultiView, to achieve accurate astrometry on the level of the thermal noise at low VLBI frequencies dominated by ionospheric residuals. We demonstrate on L-band VLBA observations how MultiView provides superior astrometry to conventional phase referencing techniques (Rioja et al. 2017). We also introduce a new trial method to detect antenna based systematic errors in the observations (Orosz et al. 2017}. All presented methods and results are based on our recent papers (Orosz et al. 2017; Rioja et al. 2017).