An Efficient Method to Compute Microlensed Light Curves for Point Sources

We present a method to compute microlensed light curves for point sources. This method has the general advantage that all micro images contributing to the light curve are found. While a source moves along a straight line, all micro images are located either on the primary image track or on the secondary image tracks (loops). The primary image track extends from -infinity to +infinity and is made of many sequents which are continuously connected. All the secondary image tracks (loops) begin and end on the lensing point masses. The method can be applied to any microlensing situation with point masses in the deflector plane, even for the overcritical case and surface densities close to the critical. Furthermore, we present general rules to evaluate the light curve for a straight track arbitrarily placed in the caustic network of a sample of many point masses.