OH absorption in the first quadrant of the Milky Way as seen by THOR M. R. Rugel, H. Beuther, S. Bihr, Y. Wang, J. Ott, A. Brunthaler, A. Walsh, S. C. O. Glover, P. F. Goldsmith, L. D. Anderson et al. (13 more) A&A, 618 (2018) A159 Published online: 23 October 2018 DOI: 10.1051/0004-6361/201731872