The Emission-Line Spectrum of Cygnus A

Spectra of Cygnus A taken at the Hale Observatories have been analysed. A line list of the nebular emission is presented. The results can be accounted for by a two-component model of the nucleus in which condensations at $${T}_\text{e}\,={10}^{4^{\circ} }\text{K}$$ produce most of the emission lines; these condensations are embedded in a tenuous plasma at $${T}_\text{e}\,\approx {10}^{6^{\circ} }\text{K}$$ . A continuing source of excitation probably exists in the optical nucleus of this radio galaxy.