The Gravitational Lens Candidate FBQ 1633+3134

We present our ground-based optical imaging, spectral analysis, and highresolution radio mapping of the gravitational lens candidate FBQ 1633+3134.This z=1.52, B=17.7 quasar appears double on CCD images with an imageseparation of 0.66 arcseconds and a flux ratio of ~3:1 across BVRI filters. Asingle 0.27 mJy radio source is detected at 8.46 GHz, coincident to within anarcsecond of both optical components, but no companion at radio wavelengths isdetected down to a flux level of 0.1 mJy (3 sigma). Spectral observationsreveal a rich metal-line absorption system consisting of a strong Mg II doubletand associated Fe I and Fe II absorption features, all at an interveningredshift of z=0.684, suggestive of a lensing galaxy. Point spread functionsubtraction however shows no obvious signs of a third object between the twoquasar images, and places a detection limit of I > 23.0 if such an objectexists. Although the possibility that FBQ 1633+3134 is a binary quasar cannotbe ruled out, the evidence is consistent with it being a single quasar lensedby a faint, metal-rich galaxy.Comment: 24 pages, 5 figures. Accepted by AJ. A calibration error affecting B and V band apparent magnitudes has been corrected. The conclusions of the paper are not change