2319+272 : a flat spectrum quasar viewed through the cluster Abell 2584.

Direct imaging data and low resolution spectroscopy of the faint (m_R_ = 18.6 mag) optical counterpart of the flat spectrum radio source 2319+272 show that it is a quasar at z = 1.253 seen through the central part of the distant Abell cluster A2584 (z ~0.12). Spectroscopy of four bright galaxies in the field revealed that only three of them are actually members of the cluster while the fourth is a barred spiral with a much smaller redshift. The quasar is located within the outer isophotes of the central pair of cluster galaxies and additional objects even closer to the line-of-sight have been detected. The flux of the source is almost certainly amplified by gravitational lensing of the foreground galaxies, and microlensing may also take place, although probably only at small optical depths. 2319+272 provides new lines-of-sight through the outskirts of several foreground galaxies, which possibly allow a study of the interstellar medium of these galaxies. The intervening matter is likely to be responsible for the high Faraday rotation measure of this radio source.