Disentangling the excitation conditions of the dense gas in M17 SW J. P. Pérez-Beaupuits, R. Güsten, M. Spaans, V. Ossenkopf, K. M. Menten, M. A. Requena-Torres, H. Wiesemeyer, J. Stutzki, C. Guevara and R. Simon A&A, 583 (2015) A107 Published online: 02 November 2015 DOI: 10.1051/0004-6361/201526441