The first confirmed case of a gravitational lens, an effect long predicted by the general theory of relativity. It consists of two images, 5.7" apart, of the same quasar, and results from the gravitational effect of an intervening cluster of galaxies that lies about 3.5 billion light-years away. The Double Quasar was discovered in 1979 and lies in the constellation Ursa Major at R.A. 10h 1.3m, Dec. +55° 54'.
