1. Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
2. Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA
3. Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
4. Bartol Research Institute, University of Delaware, Newark, Delaware 19716, USA
5. School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
6. Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA
7. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
8. Southwest Research Institute, San Antonio, Texas 78238, USA