Mass models and environment of the new quadruply lensed quasar SDSS J1330+1810

We present the discovery of a new quadruply lensed quasar. The lens system, SDSS J1330+1810 at z_s = 1.393, was identified as a lens candidate from the spectroscopic sample of the Sloan Digital Sky Survey. Optical and near-infrared images clearly show four quasar images with a maximum image separation of 1.76 arcsec, as well as a bright lensing galaxy. We measure a redshift of the lensing galaxy of z_l = 0.373 from absorption features in the spectrum. We find a foreground group of galaxies at z = 0.31, centred at ∼120 arcsec south-west of the lens system. Simple mass models fit the data quite well, including the flux ratios between images, although the lens galaxy appears to be ∼1 mag brighter than expected by the Faber-Jackson relation. Our mass modelling suggests that shear from nearby structure is affecting the lens potential.