1. Anton Pannekoek Institute for Astronomy, University of Amsterdam, NL-1098 XH Amsterdam, the Netherlands
2. Space Telescope Science Institute, Baltimore, MD 21218, USA
3. Eureka Scientific, Inc., 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017, USA
4. Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
5. College of Astronomy and Space Sciences, University of the Chinese Academy of Sciences, Beijing 100049, China
6. Sydney Institute for Astronomy, The University of Sydney, Sydney, NSW 2006, Australia
7. Department of Physics, Middlebury College, Middlebury, VT 05753, USA