THE SPECTRUM OF THE PLANETARY-NEBULA NGC 6790

International Ultraviolet Explorer (IUE) and optical region spectrosco pic observations are presented for the medium-excitation planetary neb ula (PN) NGC 6790, which displays a rich spectrum permitting applicati on of several diagnostic ratios and the calculation of a number of ion ic concentrations, N(ion)/N(H+). NGC 6790 seems to be a relatively you ng object which may represent a stage of development only slightly bey ond that of a PN such as Hb 12. The diagnostics for NGC 6790 suggest a rather large density range, although not one as great as that found i n IC 4997. An attempt is made to calculate a plausible, simple spheric ally symmetrical model. We suggest that NGC 6790 may serve as a protot ype ''standard'' for PN of intermediate age, density, and evolutionary development, Further modeling attempts would appear inappropriate unt il images of high spatial resolution become available.