Imaging polarimetry of the high-z radio galaxy 3C368

New optical polarization maps are presented which spatially resolve the elongated features of the high-z radio galaxy 3C368. The observed levels of polarization in the extended regions (∼ 13 per cent in the V waveband) and the pattern of vector orientations show that a component of the elongated structure is a giant reflection nebulosity, thus providing strong support for the beaming/scattering model for high-z radio galaxies in general. The observations also show significant dilution of the polarized light, with the level of polarisation decreasing sharply between the V-band and no filter (peak 675 nm) observations, both in the nucleus and in the extended regions. (author)