1. SUPA, School of Science and Engineering, University of Dundee , Nethergate, DD1 4HN, Dundee , UK
2. European Southern Observatory , Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München , Germany
3. INAF–Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, I-50125 Firenze , Italy
4. Department of Physics ‘E. Fermi’, University of Pisa , Largo Bruno Pontecorvo 3, I-56127 Pisa , Italy
5. INFN, Sezione di Pisa , Largo Bruno Pontecorvo 3, I-56127 Pisa , Italy
6. SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews KY16 9SS, Scotland , UK
7. Purple Mountain Observatory, Chinese Academy of Sciences , 10 Yuanhua Road, Nanjing 210023 , China
8. Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences , Konkoly-Thege Miklós út 15-17, 1121 Budapest , Hungary
9. CSFK, MTA Centre of Excellence , Konkoly-Thege Miklós út 15-17, 1121 Budapest , Hungary
10. Institute of Physics, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
11. Max Planck Institute for Astronomy , Königstuhl 17, D-69117 Heidelberg , Germany