Accurate parallax measurement toward the symbiotic star R Aquarii

Multiepoch phase-referencing VLBI (Very Long Baseline Interferometry) observations with VERA (VLBI Exploration of Radio Astrometry) were performed for the symbiotic star R Aquarii (R Aqr) from 2005 September to 2006 October. Tracing one of the v = 2, J = 1–0 SiO maser spots, we measured an annual parallax of π = 4.59 ± 0.24 mas, corresponding to a distance of $218_{-11}^{+12}\:$pc. Our result is c...