1. Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
2. Physics Department, College of Science, United Arab Emirates University, PO Box 15551, Al-Ain, UAE
3. Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160-C, Chile
4. Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg, Germany