1. Department of Physics, Christ University, Hosur Road, Bangalore 560 029, India
2. Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India
3. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
4. Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
5. Dayanand Science College, Barshi Road, Latur, Maharashtra 413512, India