1. Department of Physics and Electronics, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
2. SKA South Africa, 3rd Floor, The Park, Park Road, Pinelands 7405, South Africa
3. GEPI, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 place Jules Janssen, F-92190 Meudon, France
4. Sub-Department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK
5. Department of Astronomy, University of California, Berkeley, 501 Campbell Hall 3411, Berkeley, CA 94720, USA
6. Joint Institute for VLBI ERIC in Europe, Oude Hoogeveensedijk 4, NL-7991 PD Dwingeloo, the Netherlands