SDSS J1640+1932: a spectacular galaxy-quasar strong lens system
  We present Canada-France-Hawaii Telescope (CFHT) MegaCam observations of a
galaxy-quasar strong gravitational lens system, SDSS J1640+1932. This system,
located at z=0.195 (foreground elliptical galaxy) and z=0.778 (background
quasar), was first visually identified by us in the Sloan Digital Sky Survey
(SDSS) database. Our CFHT imaging with an angular resolution of 0.7$^{\prime
\prime}$ clearly resolves 4 lensed images and a nearly complete Einstein ring.
Modeling the system with a singular isothermal ellipsoid (SIE) total mass
distribution, we find an Einstein radius of ${2.49^{\prime
\prime}}_{-0.049}^{+0.063}$ enclosing a inferred mass of
$7.25_{-0.29}^{+0.37}\times10^{11} M_{\odot}$. The quasar and its host galaxy
have been magnified by a factor of 23, and the time delay relative to the
leading image is determined to be 23.4-25.2 days. These parameters vary
minimally when our model is fitted to the {\it{g}}-, {\it{r}}- or {\it{i}}-band
images.
