1. Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, State College, PA 16802, USA
2. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
3. Department of Physics, University of Connecticut, Storrs, CT 06269, USA
4. Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago, Chile
5. Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter Street, Madison, WI 53706, USA
6. Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Golm (Potsdam), Germany
7. Leibniz-Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
8. Indian Institute of Space Science and Technology, Thiruvananthapuram 695547, Kerala, India
9. Department of Astronomy, New Mexico State University, Las Cruces, NM 88003, USA