4 The spectral observations

Long-slit spectra were obtained from the peculiar structures discovered in the north-east neighbourhood of CTB 80. The approximate slit locations are shown in Fig. 3 as long rectangles in the north-south direction, while the equatorial coordinates of the slit centers are given in Table 3. The red lines of H$\alpha$, [N II] and [S II] are accurately established, while the bluer lines of H$\beta$, and [O III] are almost always present with a range of significance. The fluxes of the individual lines are given in Table 4 along with their signal to noise ratio as calculated by the relevant IRAF routines. Consequently, these signal to noise values do not include calibration errors which for the specific observations are, on the average, $\sim$6%. Aperture spectra extracted from the north of the corresponding slit center are designated as IIIn or IVn, while those extracted from the south are designated as IIIs or IVs (see also the caption of Table 4). Common to all spectra is the strong sulfur emission relative to H$\alpha$, indicative of shock heated gas. In addition, the ratio of the sulfur lines is close to the low density limit of $\sim$1.4-1.5 (e.g. Osterbrock 1989), characteristic of spectra from evolved supernova remnants. The medium ionization line of [O III] is present in all spectra. However, its strength relative to H$\alpha$ varies significantly. We measure a weak [O III] emission in area IVn amounting to 17% of the H$\alpha$ emission, while the maximum [O III] emission is observed in area II where it amounts to 68% of the H$\alpha$ emission (Table 4).