Elliptical Lens Model in PG1115+080

The mass distribution of the lensing galaxy of the multiple quasar PG1115+080 has been studied. Using the observational data of Christian et al. (1987, ApJ 464, 92), 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.