Wide-field spectroscopy of A1689 and A1835 with VIMOS: first results

We are using VIMOS to conduct a wide-field spectroscopic survey covering fields of 0.5 × 0.5 deg² around the X-ray luminous clusters of galaxies Abell 1689 (z=0.185) and Abell 1835 (z=0.25). Here we describe the observations and first results on the redshift distribution of subsamples of cluster galaxies to R≃22 for which we at present have obtained secure redshifts. These subsamples constitute ∼ 40% of the total spectroscopic sample and contain 525 and 630 cluster members in Abell 1689 and Abell 1835, respectively, placing them amongst the largest redshift samples available for any cluster of galaxies.