1. NASA Goddard Space Flight Center; Greenbelt Maryland USA
2. Goddard Planetary Heliophysics Institute; University of Maryland, Baltimore County; Baltimore Maryland USA
3. Harvard-Smithsonian Center for Astrophysics; Harvard University; Cambridge Massachusetts USA
4. School of Climate and Space Sciences and Engineering; University of Michigan; Ann Arbor Michigan USA
5. School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
6. LPC2E/CNRS; University of Orleans; Orleans France