Institution: | 1. Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia;2. Astronomical Observatory, Volgina 7, 11060 Belgrade 38, Serbia;3. Special Astrophysical Observatory of the Russian AS, Nizhnij Arkhyz, Karachaevo-Cherkesia 369167, Russia;4. Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51y 216, 72000 Puebla, Mexico |