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The precise analysis of properties of planetary nebulae is strongly dependenton good models for the stellar ionizing spectrum. Observations in the UV -X-ray wavelength range as well as NLTE model atmosphere calculations of spectraof their exciting stars have shown that neither blackbody fluxes nor "standard"NLTE atmosphere models which are composed out of hydrogen and helium only aregood approximations. Strong differences between synthetic spectra from thesecompared to observed spectra at energies higher than 54 eV (He II ground state)can be ascribed to the neglect of metal-line blanketing.  Realistic modeling of the emergent fluxes of hot stars in the UV - X-raywavelength range requires metal-line blanketed NLTE model atmospheres whichinclude all elements from hydrogen up to the iron-group. For this purpose, wepresent a grid (solar and halo abundance ratios) of metal-line blanketed NLTEmodel atmosphere fluxes which covers the parameter range of central stars ofplanetary nebulae.Comment: 6 pages, 5 figure

A grid of synthetic ionizing spectra for very hot compact stars from NLTE model atmospheres