Complete CLOUDY model of the main nebula. The dashed lines give the observational data, while the full lines depict the model. The spectral lines in the left panels a) and b) are used to fit the free parameters of the density law, the filling factor, and the temperature of the CSPN. The right panels c) and d) give the results derived for other lines from the best-fit model. The VLA intensities were arbitrarily scaled to the same level as the peak in Hα.