1. School of Natural Sciences, Private Bag 37, University of Tasmania, Hobart, TAS 7001, Australia
2. Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK
3. Research School of Astronomy and Astrophysics, The Australian National University, ACT 2611, Australia
4. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, Garching D-85748, Germany
5. Escola de Artes, Ciencias e Humanidades, Universidade de Sao Paulo, Rua Arlindo Bettio, 1000, Sao Paulo, SP 03828-000, Brazil
6. Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK
7. Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 Japan