Liu, JifengMcClintock, Jeffrey E.Narayan, RameshDavis, Shane W.Orosz, Jerome A.2016-08-052010Liu, Jifeng, Jeffrey E. McClintock, Ramesh Narayan, Shane W. Davis, and Jerome A. Orosz. 2010. "Erratum: "Precise Measurement of the Spin Parameter of the Stellar-Mass Black hole M33 X-7” (2008, ApJ, 679, L37).” The Astrophysical Journal 719 (1) (July 26): L109–L109. doi:10.1088/2041-8205/719/1/l109.2041-8205http://nrs.harvard.edu/urn-3:HUL.InstRepos:27814539In prior work, Chandra and Gemini-North observations of the eclipsing X-ray binary M33 X-7 have yielded measurements of the mass of its black hole primary and the system’s orbital inclination angle of unprecedented accuracy. Likewise, the distance to the binary is known to a few percent. In an analysis based on these precise results, 15 Chandra and XMM-Newton X-ray spectra, and our fully relativistic accretion disk model, we find that the dimensionless spin parameter of the black hole primary is . The quoted 1 a p 0.77 0.05 j error includes ∗ all sources of observational uncertainty. Four Chandra spectra of the highest quality, which were obtained over a span of several years, all lead to the same estimate of spin to within statistical errors (2%), and this estimate is confirmed by 11 spectra of lower quality. There are two remaining uncertainties: (1) the validity of the relativistic model used to analyze the observations, which is being addressed in ongoing theoretical work; and (2) our assumption that the black hole spin is approximately aligned with the angular momentum vector of the binary, which can be addressed by a future X-ray polarimetry mission.en-USbinaries: generalblack hole physicsgalaxies: individual (M33)X-rays: binariesJournal Article2016-08-0510.1088/2041-8205/719/1/L109