A novel approach for extracting time-delays from lightcurves of lensed quasar images

We present a new method to estimate time delays from light curves of lensed quasars. The method is based on chi (2) minimization between the data and a numerical model light curve. A linear variation can be included in order to correct for slow long-term microlensing effects in one of the lensed ima ges. An iterative version of the method can be applied in order to correct for higher-order microlensing effects. The method is tested on simulated li ght curves. When higher-order microlensing effects are present, the time de lay is best constrained with the iterative method. Analysis of a published data set for the lensed double Q 0957+561 yields results in agreement with other published estimates.