2002A&A...388..355M

We present the first CCD mosaic of the supernova remnant G 65.3+5.7 in the optical emission lines of [OII] and [OIII]. The new images reveal several diffuse and filamentary structures both inside and outside the extent of the remnant as defined by its X-ray and radio emission. The medium ionization line of [OIII]5007Å provides the sharpest view to the system, while the remnant appears less filamentary in the emission line of [OII]. There are significant morphological differences between the two images strongly suggesting the presence of incomplete shock structures. Deep long-slit spectra were taken at several different positions of G 65.3+5.7. All spectra originate from shock heated gas, while the majority of them is characterized by large [OIII]/Hβ ratios. The sulfur line ratios indicate electron densities below ∼200cm^–3, while estimates of the shock velocities lie in the range of 90-140km/s. Finally, the observed variations of the Hα/Hβ ratios may reflect the presence of intrinsic absorption affecting the optical spectra.