1608- A QUADRUPLE-LENS SYSTEM FOUND IN THE CLASS GRAVITATIONAL LENS SURVEY(656 )

The first phase of a large gravitational lens survey using the Very La rge Array at a wavelength of 3.6 cm has been completed, yielding image s for 3258 radio sources. The Cosmic Lens All-Sky Survey (CLASS) is de signed to locate gravitational lens systems consisting of multiply ima ged compact components with separations greater than 0''.2. We report here the first discovery of a gravitational lens from the survey: 1608 +656, a quadruply imaged object with a maximum separation of 2''.1. Im ages from the Palomar 5 m and Keck 10 m telescopes show the lensed ima ges and the lensing galaxy. An optical spectrum obtained with the Palo mar 5 m telescope indicates a redshift of z = 0.6304 for the lensing g alaxy. No conclusive redshift for the lensed object has been determine d, although a single strong emission line is found at 9240 Angstrom in the Keck low-resolution imaging spectrograph spectrum. The two most l ikely identifications for this line are H beta (z = 0.90) and Mg II (z = 2.30). The preliminary lens model derived from the radio image repr oduces the observed configuration and relative fluxes of the images, a s well as the position, shape, and orientation of the lensing galaxy. Because a simple mass model is able to fit the observations, we argue that this lens system is promising for determining H-0.