1. Astronomical Observatory, Taras Shevchenko National University of Kyiv, 04053 Kyiv, Ukraine
2. Main Astronomical Observatory, National Academy of Sciences, 03143 Kyiv, Ukraine
3. Crimean Astrophysical Observatory, Nauchnij, Crimea
4. Astronomical Institute, Slovak Academy of Sciences, SK-05960 Tatranská Lomnica, Slovak Republic
5. Terskol Branch, Institute of Astronomy, Russian Academy of Sciences, 361623 Russia
6. Peak Terskol Observatory, ICAMER, Research, National Academy of Sciences, Ukraine