1. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital – 263002, India
2. Department of Physics, DDU Gorakhpur University, Gorakhpur – 273009, India
3. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China
4. Department of Physics, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628-0718, USA
5. Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai – 400085, India