Constraining the location of rapid gamma-ray flares in the flat spectrum radio quasar 3C 273 B. Rani, B. Lott, T. P. Krichbaum, L. Fuhrmann and J. A. Zensus A&A, 557 (2013) A71 Published online: 02 September 2013 DOI: 10.1051/0004-6361/201321440