1608+656: A Quadruple-Lens System Found in the CLASS Gravitational Lens Survey

The first phase of a large gravitational lens survey using the Very Large Array at a wavelength of 3.6 cm has been completed, yielding images for 3258 radio sources. The Cosmic Lens All-Sky Survey, or CLASS, is designed to locate gravitational lens systems consisting of multiply-imaged compact components with separations ? 0: 00 2. We report here the first discovery of a gravitational lens from the survey: 1608+656, a quadruply-imaged object with maximum separation of 2: 00 1. Images from the Palomar 5-m and Keck 10-m telescopes show the lensed images and the lensing galaxy. An optical spectrum obtained with the Palomar 5-m Telescope indicates a redshift of z = 0:6304 for the lensing galaxy. No conclusive redshift for the lensed object has been determined, although a single strong emission line is found at 9240 A in the Keck LRIS spectrum. The two most likely identifications for this line are either Hfi (z = 0:90) or Mg II (z = 2:30). The preliminary lens model derived from the ra...