1. Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, NL-6500 GL Nijmegen, the Netherlands
2. Department of Physics, University of Warwick, Coventry CV4 7AL, UK
3. Inter-University Institute for Data Intensive Astronomy, Department of Astronomy, University of Cape Town, Private Bag X3, 7701 Rondebosch, South Africa
4. South African Astronomical Observatory, PO Box 9, 7935 Observatory, South Africa
5. Institute for Astronomy, KU Leuven, Celestijnenlaan 200D bus 2401, 3001 Leuven, Belgium
6. SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, NL-3584 CA Utrecht, the Netherlands