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For refcode 1998AJ....115...62H:
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1998AJ....115...62H ASYMMETRY IN HIGH-PRECISION GLOBAL H I PROFILES OF ISOLATED SPIRAL GALAXIES MARTHA P. HAYNES Center for Radiophysics and Space Research and National Astronomy and Ionosphere Center,1 Cornell University, Ithaca, NY 14853; haynes@astrosun.tn.cornell.edu DAVID E. HOGG National Radio Astronomy Observatory,2 520 Edgemont Road, Charlottesville, VA 22903; dhogg@nrao.edu RONALD J. MADDALENA National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944; rmaddale@nrao.edu MORTON S. ROBERTS National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903; mroberts@nrao.edu AND LIESE VAN ZEE Center for Radiophysics and Space Research and National Astronomy and Ionosphere Center, Cornell University, Ithaca, NY 14853; lvanzee@nrao.edu Received 1997 May 12; revised 1997 September 24 ABSTRACT New high signal-to-noise ratio 21 cm H I line profiles have been obtained for 104 galaxies with the Green Bank 43 m telescope. The primary sample is composed of isolated spirals with no known optical companions within a 1^deg^ radius and a median ratio of optical diameter to beamwidth of 0.17. An effort was made to ensure linearity of baseline fitting and precise flux density calibration to better than 5%. Two quantitative measures of asymmetry are applied to assess the occurrence of lopsidedness in the global H I profiles. In agreement with previous estimates, half the galaxies show significant H I profile asymmetries. The lopsidedness cannot be explained by pointing offsets but, rather, must result from noncircular motions, confusion with unidentified companions within the telescope beam, or true distortions in the H I distribution. Key words: galaxies: kinematics and dynamics - galaxies: structure
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