Image restoration and photometric monitoring of the gravitational lens Q2237+0305
Abstract
An image processing technique based on Lucy's algorithm [AJ, 79,745 (1974)] was developed and tested on CCD frames of Q 2237 + 0305 obtained at Observatoire du mont Megantic on 1990 July 27 in FWHM ~1.5" seeing and on 1990 October 16 (FWHM ~1.7"). Magnitudes were successfully obtained for the four components of this image which all lie within 1 arcsec of the lensing galaxy nucleus. Historical light curves (1986-1991) are constructed for the four images with the implementation of a "bootstrap" method. This also allows refinements to the estimates of differential extinction between the components and can detect microlensing events at the < 0.1 mag level. The results of our photometry agree well with the trends defined by other observations taken in superior seeing at the same epoch.