DISCOVERY OF EXTREME-ULTRAVIOLET RADIATION FROM THE SEYFERT-GALAXY TON S180 (=EUVE J0057-223)

We report the detection of intense EUV radiation from the Seyfert 1 ga laxy Ton S180. The source EUVE 50057-223, discovered in the Extreme-Ul traviolet Explorer all-sky survey, is only 25'' away from its optical counterpart, well within the position error circle. We present a compl ete broadband energy distribution of Ton S180 using infrared (IRAS), o ptical, ultraviolet (IUE) and X-ray (ROSAT) flux measurements, and we find that the measured EUV flux, corrected for neutral hydrogen and he lium absorption in the Galaxy, suggests the presence of a strong EUV t o soft X-ray flux excess. We briefly discuss the implications for mode ls of active galaxies.