Spectroscopic redshift for the Cl 0024+16 multiple arc system: Implications for the central mass distribution

We present a spectroscopic redshift of z = 1.675 for the well-known multipl y lensed system of arcs seen in the z = 0.39 cluster Cl 0024+16. In contras t to earlier work, we find that the lensed images are accurately reproduced by a projected mass distribution which traces the locations of the brighte st cluster elliptical galaxies, suggesting that the most significant minima of the cluster potential are not dynamically erased. The averaged mass pro file is shallow and consistent with predictions of recent numerical simulat ions. The source redshift enables us to determine an enclosed cluster mass of M(<100 kpc h(-1)) = 1.11 +/- 0.03 x 10(14) h(-1) M-circle dot (Omega = 1 ) and a mass-to-light ratio of M/L-B(<100 kpc h(-1)) = 320 +/- 30 h (M/L-B) (circle dot) (virtually independent of curvature), after correction for pas sive stellar evolution. The are spectrum contains many ionized absorption l ines and closely resembles that of the local Wolf-Rayet galaxy NGC 4217. Ou r lens model predicts a high magnification (similar or equal to 20) for eac h image and identifies a new pair of multiple images of a galaxy at a predi cted redshift of z = 1.3.