Microlensing in the double quasar SBS 1520+530

We present the results of a monitoring campaign of the double quasar SBS 1520+530 at Maidanak observatory from April 2003 to August 2004. We obtained light curves in V and R filters that show small-amplitude $\Delta m\approx 0.1$ mag intrinsic variations of the quasar on time scales of about 100 days. The data set is consistent with the previously determined time delay of $\Delta t=(130\pm3)$ days by Burud et al. (2002, A&A, 391, 481). We find that the time delay corrected magnitude difference between the quasar images is now larger by $(0.14\pm0.03)$ mag than during the observations by Burud et al. (2002). This confirms the presence of gravitational microlensing variations in this system.