Precision photometry with difference imaging in the WTS J. Zendejas, J. Koppenhoefer, R.P. Saglia, J.L. Birkby, S.T. Hodgkin, G. Kovács, D.J. Pinfield, B. Sipőcz and the RoPACS collaboration EPJ Web of Conferences, 47 (2013) 01005 Published online: 25 April 2013 DOI: 10.1051/epjconf/20134701005