1. Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetskij Pr. 13, Moscow 119992, Russia
2. Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997, Russia
3. South African Astronomical Observatory, PO Box 9, 7935 Observatory, Cape Town, South Africa
4. Southern African Large Telescope Foundation, PO Box 9, 7935 Observatory, Cape Town, South Africa
5. Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany
6. Kazan Federal University, Kremlevskaya Str 18, Kazan, Russia