Expected ultraviolet emission spectrum of a gaseous nebula

The nebular emission lines expected to be observable in the satellite ultraviolet are quantitatively discussed. The strengths of the collisionally excited lines depend on the temperature, on excitation potentials and abundances which are known and on collision strengths, which in some cases are known and in other cases are calculated or else estimated on the basis of the limit theorem. The strengths of the recombination lines are estimated from available hydrogen-like computations, and except for He II are generally small in comparison with the collisionally excited lines except at the shortest wavelengths. The expected resonance-fluorescence lines and the expected continua are also briefly discussed.