The First FIRST Gravitationally Lensed Quasar: FBQ 0951+2635

The V = 16.9 quasar FBQ 0951+2635 at redshift z = 1.24 appears double on CCD exposures taken in subarcsecond seeing. The two objects are separated by 1.″1 and differ in brightness by 0.9 mag. VLA observations show the radio source to be double with the same separation and position angle. Spectra taken with the Keck II Telescope show the two components to have nearly identical emission-line spectra, but with somewhat different absorption-line systems. Subtraction of two stellar point-spread functions from the pair of components consistently leaves a residual object. Depending upon whether this third object is extended or a point source, it may be as much as 1/10 or as little as 1/100 as bright as the brighter QSO component. The observations leave little doubt that the two brighter objects are gravitationally lensed images of the same quasar. The third object might be either the lensing galaxy or a third image of the quasar, but both interpretations have serious shortcomings.