SDSS J1029+2623:: A gravitationally lensed quasar with an image separation of 22.5

We report the discovery of a cluster-scale lensed quasar, SDSS J1029 + 2623, selected from the Sloan Digital Sky Survey. The lens system exhibits two lensed images of a quasar at z(s) = 2.197. The image separation of 22''.5 makes it the largest separation lensed quasar discovered to date. The similarity of the optical spectra and the radio loudnesses of the two components support the lensing hypothesis. Images of the field show a cluster of galaxies at z(1)similar to 0.55 that is responsible for the large image separation. The lensed images and the cluster light centre are not collinear, which implies that the lensing cluster has a complex structure.