Is There a Need for an Improved Celestial Reference Frame ? Johnston, Kenneth ; Wehrle, A. E. ; Makarov, V. ; Murphy, D. W. ; Unwin, S. C. ; Zacharias, N. ; Fey, A. L. ; Ojha, R. ; Boboltz, D. A. ; Lazio, T. J. ; Olling, R. F. ; Gaume, R. A. Abstract Publication: astro2010: The Astronomy and Astrophysics Decadal Survey Pub Date: 2009 Bibcode: 2009astro2010S.143J