X-RAY OUTBURST OF THE PECULIAR SEYFERT-GALAXY IC-3599

We report optical, soft X-ray, and UV observations of the peculiar Sey fert galaxy IC 3599 using data obtained with ROSAT and IUE. Most remar kably, we discovered a rapid decrease of the X-ray flux by a factor of about 100 within one year and a more gradual decrease thereafter. The X-ray spectrum of IC3599 was soft at flux maximum and became even sof ter as the flux decreased. Simultaneously with the late decrease of th e X-ray flux, we observed a decrease in the strength of highly ionized optical iron lines. We discuss several explanations for this behaviou r including an accretion disk instability and tidal disruption of a st ar orbiting a central massive black hole.