The optical spectrum of the planetary nebula NGC 6543

With the Hamilton echelle spectrograph at the Lick Observatory, emission-ri ch spectral lines of the planetary nebula NGC 6543 were secured in the wave length range from 3550 to 10 100 Angstrom. We chose two bright regions, sim ilar to 8 arcsec east and similar to 13 arcsec north of the central star, t he physical conditions and chemical abundances of which may differ as a res ult of the different physical characteristics involving the mass ejection o f different epochs. By combining Hamilton echelle observations with archive UV data secured with the International Ultraviolet Explorer (IUE), we obta in improved diagnostics and chemical compositions for the two observed regi ons. The diagnostic diagram gives the average value of T-e = 8000 similar t o 8300 K, and the electron number density near N-e similar to 5000 cm(-3) f or most ions, while some low-excitation lines indicate much higher temperat ures, i.e. T-e similar to 10 000 K. With the construction of a photoionizat ion model, we try to fit the observed spectra in a self-consistent way: thu s, for most elements, we employ the same chemical abundances in the nebular shell; and we adopt an improved Sobolev approximation model atmosphere for the hydrogen-deficient Wolf-Rayet type central star. Within the observatio nal errors, the chemical abundances do not seem to show any positional vari ation except for helium. The chemical abundances of NGC 6543 appear to be t he same as in average planetary nebulae. The progenitor star may have been an object of one solar mass, most of the heavier elements of which were les s plentiful than in the Sun.