VERA Observations of SiO Masers in the Symbiotic Star R Aquarii

We present phase-referenced maps of the SiO maser transitions $v =$ 1 $J =$ 1-0 and $v =$ 2 $J =$ 1-0 from the symbiotic stellar system R Aquarii, which hosts an evolved AGB star plus a hot companion. Observations were performed at two epochs: 2004.98 and 2005.98. Accurate absolute coordinates and proper motions of the emission centroid were obtained; the errors expected for these parameters are a...