Argon, AliceGreenhill, LincolnMoran, JamesReid, MarkMenten, K. M.Inoue, M.2017-04-072004Argon, A. L., L. J. Greenhill, J. M. Moran, M. J. Reid, K. M. Menten, and M. Inoue. 2004. “The IC 133 Water Vapor Maser in the Galaxy M33: A Geometric Distance.” The Astrophysical Journal 615 (2) (November 10): 702–719. doi:10.1086/424731.0004-637Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:32095191We report on the results of a 14 year long VLBI study of proper motions in the IC 133 H2O maser source in the galaxy M33. The method of Ordered Motion Parallax was used to model the 3-dimensional structure and dynamics of IC 133 and obtain a distance estimate, 800 ± 180 kpc. Our technique for determining the distance to M33 is independent of calibrations common to other distance indicators, such as Cepheid Period-Luminosity relations, and therefore provides an important check for previous distance determinations.en-USgalaxies: individual (M33)interferometryISM: individual (IC 133)masersJournal Article2017-02-2820042017-04-0710.1086/424731