of Spectral Observations. Jorn Helbert, Mario. D’Amore, Alessandro Maturilli, Noam R. Izenberg, Ann L. Sprague, Gregory M. Holsclaw, James W. Head, William E. McClintock, David T. Blewett and Sean C. Solomon, Institute for Planetary Research, DLR, 12489 Berlin, Germany (joern.helbert@dlr.de); Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA; Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA; Department of Geological Sciences, Brown University, Providence, RI 02912, USA; Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA