Rest-wavelength HST spectra of the nucleus and knots, showing the spectral regions around H and H. The data points are represented as small squares and the best fit as a solid line; the lower line shows the residuals. On the upper panels (spectra of the nucleus), the individual components are also drawn. All spectra were shifted upwards, so the continuum and residuals do not overlap; the origin of the vertical (flux) scales are, therefore, arbitrary