1. Department of Theoretical Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata 700106, India
2. Inter University Centre for Astronomy & Astrophysics (IUCAA), Pune 411007, India
3. Rautara MNM High School, Habra, North 24 PGS, West Bengal, India