1. Centre for Astrophysics, University of Southern Queensland, Toowoomba, QLD 4350, Australia
2. Max Planck Institut for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen, Germany
3. Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
4. IRAP (Institut de Recherche en Astrophysique et Planétologie), Université de Toulouse, CNRS, CNES, UPS, 14 Avenue Edouard Belin, F-31400 Toulouse, France
5. School of Physics, Trinity College Dublin, The University of Dublin, College Green, Dublin-2, D02 PN40 Ireland
6. LUPM, Université de Montpellier, CNRS, Place Eugéne Bataillon, F-34095 Montpellier, France
7. Department of Physics & Astronomy, University of Exeter, Stoker Road, Devon, Exeter EX4 4QL, UK
8. SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK