UV observations of planetary nebulae

It is noted that present information indicates that carbon abundance in planetary nebulae goes from one order of magnitude higher than solar abundance from weak permitted lines in the visible spectrum of C(+), C(2+) to approximately the solar values obtained from broadband observations with the ANS satellite. In order to clarify this discrepancy, attention is given to accurate spectroscopic observations obtained with the IUE satellite. Preliminary results relative to the planetary nebula NGC 7027 are presented and discussed. Finally, it is found that the carbon abundance in this object is significantly higher than the solar one.