Mass Along the Line of Sight to the Gravitational Lens B1608+656: Galaxy Groups and Implications for H_0

C. D. Fassnacht, R. R. Gal, L. M. Lubin +3

We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z…