Elliptical Lens Model in PG 1115+080

The mass distribution of the lensing galaxy of the multiple quasar PG 1115+080 has been studied. Using the observational data of Christian et al. (1987, AAA 43.159.012), we applied a single elliptical lens model with a softened power-law behavior. It has been revealed that the image positions, amplifications, and time delays of this lensing system cannot be explained by the single transparent lens model. We compare this elliptical lens model with a multipole expansion model.