1. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
2. ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), Mail H29, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
3. South African Radio Astronomy Observatory, 2 Fir Street, Black River Park, Observatory 7925, South Africa
4. School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
5. Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK