Accurate galactic 21-cm H I measurements with the NRAO Green Bank Telescope A. I. Boothroyd, K. Blagrave, F. J. Lockman, P. G. Martin, D. Pinheiro Gonçalves and S. Srikanth A&A, 536 (2011) A81 Published online: 13 December 2011 DOI: 10.1051/0004-6361/201117656