First optical light from the supernova remnant G 17.4-2.3

Deep optical CCD images of the supernova remnant G 17.4{2.3 were obtained and faint emission has been discovered therein. The images, taken in the emission lines of H +( Nii), (S ii )a nd (Oiii), reveal lamentary structures in the east, south{east area, while diuse emission in the south and central regions of the remnant is also present. The radio emission in the same area is found to be well correlated with the brightest optical lament. The flux calibrated images suggest that the optical lamentary emission originates from shock- heated gas ((S ii)/H >0.4), while the diuse emission seems to originate from an H ii region ((S ii)/H <0.3). Furthermore, deep long{slit spectra were taken at the bright (O iii) lament and clearly show that the emission originates from shock heated gas. The (O iii) flux suggests shock velocities into the interstellar \clouds" greater than 100 km s 1 , while the (S ii) 6716=6731 ratio indicates electron densities240 cm 3 . Finally, the H emission has been measured to be between 7 to 20 10 17 erg s 1 cm 2 arcsec 2 .