Discovery of optical emission from the supernova remnant G 32.8-0.1 (Kes
  78)
  Deep optical CCD images of the supernova remnant G 32.8-0.1 were obtained
where filamentary and diffuse emission was discovered. The images were acquired
in the emission lines of Halpha+[N II] and [S II]. Filamentary and diffuse
structures are detected in most areas of the remnant, while no significant [O
III] emission is present. The flux-calibrated images suggest that the optical
emission originates from shock-heated gas since the [S II]/Halpha ratio is
greater than 1.2. The Spitzer images at 8 micron and 24 micron show a few
filamentary structures to be correlated with the optical filaments, while the
radio emission at 1.4 GHz in the same area is found to be very well correlated
with the brightest optical filaments. Furthermore, the results from deep
long-slit spectra also support the origin of the emission to be from
shock-heated gas ([S II]/Halpha > 1.5). The absence of [O III] emission
indicates slow shocks velocities into the interstellar "clouds" (< 100 km/s),
while the [S II] 6716/6731 ratio indicates electron densities up to ~200
cm^{-3}. Finally, the Halpha emission is measured to lie between 1.8 to 4.6 x
10^{-17} erg/s/cm^2/arcsec^2, while from VGPS HI images a distance to the SNR
is estimated to be between 6 to 8.5 kpc.
