DISCOVERY OF AN EXTENSIVE OPTICAL NEBULA AROUND THE SYMBIOTIC NOVA V1016-CYGNI

We present the discovery of an extended nebula of diameter approximately 24 arcsec around the symbiotic nova V1016 Cyg from long-slit high-resolution spectroscopy of the H-alpha, He II lambda-468.6-nm and [O III] lambda-500.7-nm emission lines. The existence of the nebula is confirmed by CCD images obtained in [O III]. The nebula was mapped spectroscopically but the profile changes are difficult to explain in simple terms. The extent of the nebulosity is similar to that inferred for a cool dust component by IRAS observations, for a distance of 0.6 kpc.