1. Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany
2. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
3. Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
4. School of Earth and Space Exploration, Arizona State University, Tempe AZ, USA