Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope   Imaging. IV: Measurement for Sculptor
  This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. 
S. Piatek, C. Pryor, P. Bristow, E. W. Olszewski, H. C. Harris, M.   Mateo, D. Minniti, C. G. Tinney