OGLE-III photometry of QSO 2237+0305 is available from the OGLE Internet
archive. Data files contain photometry of all components of the Huchra's
lens (A-D) and two comparison stars. See README file.
Photometry of QSO 2237+0305 was obtained with image subtraction
technique - based in large part on DIA implementation of this technique by
After the 2006 observing season the OGLE-III data of QSO 2237+0305 were
calibrated and tied to the same photometric scale as OGLE-II photometry
of this object. Thus, OGLE-II and OGLE-III photometry constitue now a
homogeneous data set starting in 1997.