G-76.9+1.0, A SUPERNOVA REMNANT WITH UNUSUAL PROPERTIES

G 76.9 + 1.0 is a non-thermal source near the galactic plane. VLA obse rvations of the object at 1.49, 4.86 and 8.44 GHz are presented. The i ntegrated flux density at 1.49 GHz is 1.8 Jy. An extended envelope of size 9' x 12' surrounds a central structure of two lobes, separated by approximately 3', joined by a bridge of emission. The spectral index is alpha=0.62+/-0.04 (where S is-proportional-to nu(-alpha)). The appa rent elliptical shape at low levels may be partly produced by emission from a background ridge. The emission from G 76.9 + 1.0 is polarized, and the rotation measure (RM) is -283 +/-75 rad m-2. Comparison of th is value with the RM of extragalactic sources suggests that G 76.9 + 1 .0 is more distant than 7 kpc and could be extragalactic. G 76.9 + 1.0 cannot be a normal galaxy, primarily because it is deficient in infra red emission. The two-lobed structure is suggestive of a radio galaxy, but the steep outer edge, characteristic of radio galaxies, is absent in this object. G 76.9 + 1.0 strongly resembles two objects which are acknowledged SNRs, G 18.9-1.1 and DA 495. It is interpreted as a fill ed-centre SNR, whose steep spectral index may possibly be explained by the effects of age. At a distance of 7 kpc, its size is approximately 18 x 24 pc.