1. Department of Physics, McGill University , 3600 rue University, Montréal, QC H3A 2T8, Canada
2. McGill Space Institute , 3550 rue University, Montréal, QC H3A 2A7, Canada
3. Department of Physics, Bard College , 30 Campus Road, Annandale-On-Hudson, NY 12504, USA
4. LESIA – Observatoire de Paris , Section de Meudon 5, place Jules Janssen, F-92195 Meudon Cedex, France