While the rotation curve of the inner Galactic disk is well determined, study of the outer rotation curve requires observational measurements of distances and proper motions of individual sources in the Outer Galaxy. We report astrometric observation for water maser sources in the Outer Galactic disk conducted with VERA, aiming to measure the Outer Rotation Curve. We have measured annual parallaxes and proper motions for these objects. Our result was consistent with recent other works based on astrometry and classical Cepheid observations. Epicyclic frequency seems to suggest that 2 and 4 spiral mode are dominant in the inner and outer Galaxy, respectively.

We made dynamical black hole mass measurements from nineteen Seyfert 2 galaxies which host sub-parsec H2O maser disks using the H2O megamaser technique. The nearly perfect Keplerian rotation curves in many of these maser systems guarantee the high accuracy and precision of the black hole mass measurements. With the stellar velocity dispersion (σ∗) of the galaxy bulges measured with the Dupont 2.5 m telescope at Las Campanas Observatory in the South and the Apache Point Observatory (APO) 3.5m telescope in the North, we found that H2O maser galaxies, most of which host pseudo bulges rather than classical bulges, do not all follow the MBH–σ∗ relation shown in the literature. This result is well consistent with the latest findings by Kormendy & Ho (2013) that only early type galaxies and galaxies with classical bulges follow a tight MBH–σ∗ relation. Such a tight correlation may not exist in pseudo bulge galaxies.