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 CCDexposures 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 tobe double with the same separation and position angle. Spectra taken with theKeck II telescope show the two components to have nearly identical emissionline spectra, but with somewhat different absorption line systems. Subtractionof two stellar point spread functions from the pair of components consistentlyleaves a residual object. Depending upon whether this third object is extendedor a point source it may be as much as 1/10 or as little as 1/100 as bright asthe brighter QSO component. The observations leave no doubt that the 2 brighterobjects are gravitationally lensed images of the same quasar. The third objectmight be either the lensing galaxy or a third image of the quasar, but bothinterpretations have serious shortcomings.Comment: LaTex, 19 pages including 5 ps figures; submitted to A