Evidence for shock-heated gas in the Hopkins Ultraviolet Telescope spectrum of NGC 1068

The paper presents FUV spectra of the NGC 1068 Seyfert 2 galaxy, obtained with the Hopkins Ultraviolet Telescope (HUT) during the flight of Astro-1 aboard the Space Shuttle Columbia in December 1990, revealing moderately strong C III 977-A and N III 991-A emission lines, which have never been seen before in spectra of AGNs. It is noted that the emission-line spectrum of NGC 1068 qualitatively resemble the HUT spectrum of a radiative shock in the Cygnus Loop supernova remnant (Blair et al., 1991), suggesting that shock heating may contribute significantly to the line emission.