1999ApJ...513..592B

We report the discovery of an arclike object 27" from the center of the cD galaxy in the redshift z=0.066 cluster A2124. Observations with the Keck II telescope reveal that the object is a background galaxy at z=0.573, apparently lensed into an arc of length ∼8".5 and total R magnitude m_R=20.86±0.07. The width of the arc is resolved; we estimate it to be ∼0".6 after correcting for seeing. A lens model of the A2124 core mass distribution consistent with the cluster galaxy velocity dispersion reproduces the observed arc geometry and indicates a magnification factor ≳9. With this magnification, the strength of the [O II] λ3727 line implies a star formation rate of ∼0.4 h^–2 M_☉.yr^–1. A2124 thus appears to be the lowest redshift cluster known to exhibit strong lensing of a distant background galaxy.