Application of the contouring method to extended microlensed sources

The method devised by Lewis et al. for calculating the light curve of a mic rolensed point source is expanded to two dimensions to enable the calculati on of Light curves of extended sources. This method is significantly faster than the ray-shooting method that has been used in the past. The increased efficiency is used to obtain much higher resolution Light curves over incr eased time scales. We investigate the signatures arising from different sou rce geometries in a realistic microlensing model. We show that a large frac tion of high-magnification events (HMEs) in image A of Q2237+0305 involve o nly one caustic, and could therefore yield information on the structure of the quasar continuum through the recognition of a characteristic event shap e. In addition, the cataloguing of HMEs into morphological type will, in th eory, enable the direction of the transverse motion, as well as the source size, to be obtained from long-term monitoring.