1. Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão 1226, São Paulo, SP 05508-900, Brazil
2. Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha, 55134-441, Iran
3. European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching b. München, Germany
4. Department of Physics Astronomy, University of Toledo, MS111 2801 West Bancroft Street, Toledo, OH 43606, USA
5. American Association of Variable Star Observers (AAVSO), Cambdrige, MA, USA
6. European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Casilla 19001, Santiago 19, Chile