1994A&A...289L..15M

We report on the detection of an excess of faint blue galaxies located in the center of the shear field detected by Bonnet et al. (1993). By using ultra-deep B and I CCD images obtained at the prime focus of CFHT, we computed isopleth contour maps by color intervals and found an excess of blue galaxies exactly centered on the center of the shear field (found by Bonnet et al.), with a small additional clump close to the double quasar. The angular size of the region with the density excess, as well as the color and surface brightness of the galaxies are evidences that we have detected a cluster of galaxies at redshift larger than 1. The faint blue galaxies are not distorted (no detectable shear) as expected for a lens responsible for the shear pattern. We discuss the consequences on the distance of the faintest sheared galaxies and on the usefullness of the weak shear technique for cosmology.