PoS(CMB2006)071 SPIDER: A Balloon-Borne Polarimeter for Measuring Large Angular Scale CMB B-modes Carrie MacTavish * , Dick Bond, Olivier Doré CITA, University of Toronto, Canada E-mail: cmactavi@cita.utoronto.ca Rick Bihary, Tom Montroy, John Ruhl Department of Physics, Case Western Reserve University, USA Peter Ade, Carole Tucker Cardiff University, U.K. James Bock, Warren Holmes, Jerry Mulder, Anthony Turner NASA, Jet Propulsion Laboratory, USA Justus Brevik, Abigail Crites, Sunil Golwala, Viktor Hristov, Bill Jones, Chao-Lin Kuo, Andrew Lange, Peter Mason, Amy Trangsrud Division of Physics, Math and Astronomy, California Institute of Technology, USA Carlo Contaldi Theoretical Physics Group, Imperial College, UK Brendan Crill IPAC, California Institute of Technology, USA Lionel Duband Commissariat A L’energie Atomique, France Mark Halpern Deptarment of Physics and Astronomy, University of British Columbia, Canada c  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/