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Observations of H$_2$O masers from circumnuclear disks in active galaxies forthe Megamaser Cosmology Project allow accurate measurement of the mass ofsupermassive black holes (BH) in these galaxies. We present the Very LongBaseline Interferometry (VLBI) images and kinematics of water maser emission insix active galaxies: NGC~1194, NGC~2273, NGC~2960 (Mrk~1419), NGC~4388,NGC~6264 and NGC~6323. We use the Keplerian rotation curves of these sixmegamaser galaxies, plus a seventh previously published, to determine accurateenclosed masses within the central $\sim0.3$ pc of these galaxies, smaller thanthe radius of the sphere of influence of the central mass in all cases. We alsoset lower limits to the central mass densities of between 0.12 and 60 $\times10^{10} M_{\odot}$~pc$^{-3}$. For six of the seven disks, the high centraldensities rule out clusters of stars or stellar remnants as the centralobjects, and this result further supports our assumption that the enclosed masscan be attributed predominantly to a supermassive black hole. The seven BHshave masses ranging between 0.76 and 6.5$\times$10$^7 M_{\odot}$. The BH masserrors are $\approx11$\%, dominated by the uncertainty of the Hubble constant.We compare the megamaser BH mass determination with other BH mass measurementtechniques. The BH mass based on virial estimation in four galaxies isconsistent with the megamaser BH mass given the latest empirical value of$\langle f \rangle$, but the virial mass uncertainty is much greater. MCPobservations continue and we expect to obtain more maser BH masses in thefuture.

The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks