Location of γ-ray emission and magnetic field strengths in OJ 287 J. A. Hodgson, T. P. Krichbaum, A. P. Marscher, S. G. Jorstad, B. Rani, I. Marti-Vidal, U. Bach, S. Sanchez, M. Bremer, M. Lindqvist et al. (12 more) A&A, 597 (2017) A80 Published online: 06 January 2017 DOI: 10.1051/0004-6361/201526727