  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).

Instrumentation and Methods for Astrophysics