PKS-0208-512 DETECTED AT MEV ENERGIES BY COMPTEL - A NEW MEV-BLAZAR CANDIDATE

We report evidence for intense MeV emission of the blazar-type AGN PKS 0208-512 from two COMPTEL observations in May-June 1993. No significa nt indication was seen during a series of earlier observations perform ed in the second half of 1991. EGRET detected high-energy gamma-rays d uring both periods, with similar average fluxes in both (and a short f lare in September 1991). We argue that the MeV emission from PKS 0208- 512 seems to represent a distinct spectral component, characterized by either a bumped shape or strong time variability, or possibly both. T his might be a valuable clue in our understanding of ''MeV Blazars'' ( i.e. blazars that are exceptionally bright at MeV energies), suggestin g a possibly transient nature of the MeV-blazar phenomenon. As a conse quence, essentially all gamma-ray blazars might contribute to the MeV bump in the diffuse cosmic background radiation during certain epochs rather than any specific sub-class.