2002A&A...383.1011M

We present the first calibrated CCD images of the faint supernova remnant G 114.3+0.3 in the emission lines of [OII], [OIII], Hα+[NII] and [SII]. The deep low ionization CCD images reveal diffuse emission in the south and central areas of the remnant. These are correlated with areas of intense radio emission, while estimates of the [SII]/Hα ratio suggest that the detected emission originates from shock heated gas. In the medium ionization image of [OIII] we discovered a thin filament in the south matching very well the outer radio contours. This filament is not continuous over its total extent but shows variations in the intensity, mainly in the south-west, suggesting inhomogeneous interstellar clouds. Deep long-slit spectra were also taken along the [OIII] filament clearly identifying the observed emission as emission from shock heated gas. The Hα emission is a few times 10^–17erg/s/cm²/arcsec², while the variations seen in the [OIII] flux suggest shock velocities into the interstellar clouds around or below 100km/s. The sulfur line ratio approaches the low density limit, implying electron densities less than ∼500cm^–3.