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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).
High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining trigonometric pa
The goal of this paper is to establish the requirements of a barycentric correction with an RMS of $lesssim 1$ cm/s, which is an order of magnitude better than necessary for the Doppler detection of true Earth analogs ($sim9$ cm/s). We describe the t
The radio sky at lower frequencies, particularly below 20 MHz, is expected to be a combination of increasingly bright non-thermal emission and significant absorption from intervening thermal plasma. The sky maps at these frequencies cannot therefore
We present a technique-led review of the progression of precise radio astrometry, from the first demonstrations, half a century ago, until to date and into the future. We cover the developments that have been fundamental to allow high accuracy and pr
High precision astrometry provides the foundation to resolve many fundamental problems in astrophysics. The application of astrometric studies spans a wide range of fields, and has undergone enormous growth in recent years. This is as a consequence o