1. South African Astronomical Observatory, PO Box 9, 7935 Observatory, Cape Town, South Africa
2. Southern African Large Telescope Foundation, PO Box 9, 7935 Observatory, Cape Town, South Africa
3. Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow 119992, Russia
4. Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, Karachai-Circassia 369167, Russia