Astrometry of W49N - OH43.8-0.1 H2O maser pair with VERA
  We present the results of multi-epoch VERA observations of W49N - OH43.8-0.1 water maser pair. Based on the dual-beam VLBI observation with VERA, we successfully obtained the phase-referenced maps of OH43.8-0.1 with respect to the W49N reference spot for 3 epochs with a time span of 6 months. The maps were in good agreement with previous studies obtained with a single-beam VLBI, and were also consistent with each other with an accuracy of about 0.2 mas. Moreover, there are systematic, rather linear displacements of maser feature positions, which may be the relative proper motions of maser features caused by the Galactic rotation as well as internal motions of individual maser features. 
Mareki Honma (VERA Project, NAOJ, Mitaka, Japan), et al