Simultaneous NFW modelling of CL 1701+6414 and A 2246. Each panel shows the dependencies between two of the four parameters, with the other two marginalised. Solid confidence contours (1σ, 2σ, 3σ) denote the default case, using the ROSAT centres; dashed contours denote models centred on the S-peaks. The respective parameters minimising are indicated by a filled circle and a upward triangle. Sets of thin contours denote the confidence contours and parameters minimising obtained from the analogous analysis of the CFHT lensing catalogue. The best-fit values for the CFHT data are marked by downward- and upward-pointing triangles for the ROSAT and S-peak centres, respectively.