The innermost region of the water megamaser radio galaxy 3C 403 A. Tarchi, A. Brunthaler, C. Henkel, K. M. Menten, J. Braatz and A. Weiß A&A, 475 2 (2007) 497-506 Published online: 24 September 2007 DOI: 10.1051/0004-6361:20078317