1. Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 002, India
2. School of Studies in Physics and Astrophysics, Pandit Ravishankar Shukla University, Chattisgarh 492 010, India
3. INAF Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy
4. Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India
5. Department of Physics & Astrophysics, University of Delhi, Delhi 110 007, India
6. Department of Physics and Astronomy, George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy, Texas A&M University, 4242 TAMU, College Station, TX 77843, USA