1. Astrophysics, Department of Physics, University of Oxford, DWB, Keble Road, Oxford OX1 3RH, UK
2. SOFIA Science Center, NASA AmesResearch Center, Moffett Field, CA 94035, USA
3. Department of Physics and Astronomy, University of Texas at San Antonio,1 UTSA Circle, San Antonio, TX 78249, USA
4. Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
5. Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia S/N, E-18008 Granada, Spain
6. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan