1. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
2. Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
3. Special Astrophysical Observatory of the Russian Academy of Sciences (SAO), Nizhnij Arkhyz 369167, Russia
4. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany