The optical gravitational lensing experiment monitoring of QSO 22371+0305

We present results from 2 yr of monitoring of Huchra's lens (QSO 2237 + 030 5) with the 1.3 m Warsaw telescope on Las Campanas, Chile. Photometry in th e V band was done using a newly developed method for image subtraction. Rel iable subtraction without Fourier division removes all complexities associa ted with the presence of a bright lensing galaxy. With the positions of the lensed images adopted from Hubble Space Telescope (HST) measurements, it i s relatively easy to fit the variable part of the flux in this system, as o pposed to modeling the underlying galaxy. For the first time, we observed s mooth light variation over a period of a few months, which can be naturally attributed to microlensing. We also describe automated software capable of real-time analysis of the images of QSO 2237 + 0305. It is expected that s tarting from the next observing season in 1999, an alert system will be imp lemented for high-amplification events in this object. The time sampling an d photometric accuracy achieved should be sufficient for early detection of caustic crossings.