1. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263001, India
2. School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Amanaka G.E. Road, Raipur 492010, India
3. Department of Physics, The College of New Jersey, PO Box 7718, Ewing, NJ 08628, USA