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 images. An iterative version of the method can be applied in order to correct for higher order microlensing effects. The method is tested on simulated light curves. When higher order microlensing effects are present the time delay is best constrained with the iterative method. Analysis of a published data set for the lensed double Q0957+561 yields results in agreement with other published estimates.