1. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea
2. Indian Institute of Astrophysics, Block II, Koramangala, Bangalore 560 034, India
3. National Institute of Technology, Tiruchirappalli - 620015, India
4. Department of Physics & Astronomy, University of Southampton, Southampton, SO17 1BJ, UK