CONTINUUM AND CIII] MICROLENSING IN Q2237+0305 AND THE QUASAR GEOMETRY

New photometry of Q2237 + 0305 in V and C III] light obtained with HRCam at the CFHT on 1991 October 10 is combined with earlier data to show that, at that epoch, component B was amplified by 0.5 mag in the continuum, with a concurrent change of its (V - C III]) color, and that component A had undergone a U-shape amplification event in 1988-1989. The light curves and color change indicate that, for an assumed transverse velocity of 600 km s-1, the continuum region of the quasar is < 1 x 10(15) cm in radius and that the broad-line region is probably > 10 times larger. It is noted that, in the absence of microlensing and differential extinction, all four bright images of Q2237 + 0305 would have the same brightness to within < 10 %. The signal-to-noise ratio of the C III] image proved insufficient to detect a faint, central fifth image of the quasar which must then be > 4 mag fainter than the brighter components of the mirage.