Optical Gravitational Lensing Experiment. OGLE 2000-BUL-43: A   Spectacular Ongoing Parallax Microlensing Event. Difference Image Analysis
  We present the photometry and theoretical models for a Galactic bulge microlensing event OGLE-2000-BUL-43. The event is very bright with I=13.54 mag, and has a very long time scale, t_E=156 days. The long time scale and its light curve deviation from the standard shape strongly suggest that it may be affected by the parallax effect. We show that OGLE-2000-BUL-43 is the first discovered microlensing event, in which the parallax distortion is observed over a period of 2 years. Difference Image Analysis (DIA) using the PSF matching algorithm of Alard & Lupton enabled photometry accurate to 0.5%. All photometry obtained with DIA is available electronically. Our analysis indicates that the viewing condition from a location near Jupiter will be optimal and can lead to magnifications ~ 50 around January 31, 2001. These features offer a great promise for resolving the source (a K giant) and breaking the degeneracy between the lens parameters including the mass of the lens, if the event is observed with the imaging camera on the Cassini space probe. 
I. Soszynski, K. Zebrun, P.R. Wozniak, S. Mao, A. Udalski, M.   Szymanski, M. Kubiak, G. Pietrzynski, O. Szewczyk, L. Wyrzyk...