AD warmly acknowledges the award of an international Macquarie University Research Excellence Scholarship (iMQRES). QAP acknowledges support from Macquarie University and the Australian Astronomical Observatory. We wish to thank Nick Wright and Michael Barlow for interesting discussions. We are grateful to David J. Frew for the initial help and discussion. We thank Anna V. Kovacevic for carrying out the May 2009 2.3 m observing run, and Lizette Guzman-Ramirez for assisting her with it. We also thank Travis Stenborg for assisting AD with the 2012 August 2.3 m observing run. AD thanks Milorad Stupar for his assistance in the reduction process. We would like to thank the staff at the ANU Siding Spring Observatory for their support, especially Donna Burton. This work was supported by the NCI National Facility at the ANU. We would also like to thank an anonymous referee for helpful suggestions that greatly improved the paper.