1. Main Astronomical Observatory of the National Academy of Sciences of Ukraine 27 Akademik Zabolotny St. Kyiv 03143 Ukraine
2. Astronomical Observatory Taras Shevchenko National University of Kyiv 3 Observatorna St. 04053 Kyiv Ukraine
3. Department of Mathematics Birla Institute of Technology and Science‐Pilani, Hyderabad Campus Hyderabad 500078 India