Detection of broad ultraviolet Fe II lines in the spectrum of NGC 1068*

Ultraviolet observations of the nucleus of NGC 1068, obtained by the IUE over a period of 5 yr, are combined to give a high signal-to-noise spectrum of this source. The ultraviolet stellar continuum, obtained by comparison with ground-based data, is subtracted to show the nuclear non-stellar component. The resulting spectrum shows clearly the presence of strong broad Fe II emission bands similar to those observed in many broad-line objects. Broad profiles are also seen in other strong emission lines. These observations confirm the recent discovery of an optical Seyfert type 1 spectrum in NGC 1068 by Antonucci & Miller. Some of our findings do not support the claim by Antonucci and Miller that the polarized fraction of the nuclear flux is wavelength independent. The non-stellar continuum is much flatter than deduced in previous investigations and not very different from that observed in many Seyfert 1 nuclei. It did not vary by more than 15 per cent over the 5 yr period. We suggest that a search for the broad ultraviolet Fe II lines may be the best way to look for a ‘hidden Seyfert 1 nucleus’ in other narrow-line objects.