The M31 Velocity Vector. I. Hubble Space Telescope Proper-motion Measurements

  title={The M31 Velocity Vector. I. Hubble Space Telescope Proper-motion Measurements},
  author={Sangmo Tony Sohn and Jay Anderson and Roeland van der Marel},
  journal={The Astrophysical Journal},
We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars… Expand
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Numerical Recipes in Fortran 77
data types 2/xiii, 1030 Accelerated convergence of series 160ff.,
Appropriately scaled and rotated boxes denote our three target fields (labeled). The underlying gray shading represents the density of stars from the map
  • 2006