1. Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
2. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA
3. Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
4. South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa
5. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
6. Warsaw University Observatory, Aleje Ujazdowskie 4, PL-00-478 Warsaw, Poland