Radio structures of Seyfert galaxies. III. Radio and optical observations of NGC 5548.

The VLA has been used to map the nuclear radio source of the Seyfert galaxy NGC 5548, at 1465 and 4885 MHz, showing it to comprise an unresolved core which coincides with the optical continuum nucleus and two diffuse lobes which straddle it at PA 165 deg. Total source extent is 5.9 kpc. Optical spectrophotometry of the Seyfert nucleus and inner galaxy at and near the radio lobes has been obtained. The off-nuclear spectra show such highly excited emission lines as forbidden line O III 5007 A, which is much greater than H-alpha, along with a late-type stellar continuum. The radio lobes may have been energized from the active nucleus, and represent a low luminosity example of the double radio source phenomenon.