Far UV study on the non-thermal activity in the narrow line galaxies NGC 4507 and NGC 5506

The narrow line high excitation galaxies NGC 4507 and NGC 5506 were observed with the IUE satellite. The continua of both galaxies, when combined with optical observations, show a flattening at log nu >14.9. The reddening correction cannot be estimated with accuracy. The UV non-stellar component is hard; after reddening correction it can be fitted with a power law, f/sub nu / varies as nu /sup - alpha /. The energy content in the Lyman continuum is large enough to power the narrow line region providing the coverage factor is of order unity. In the case of NGC 4507 the spectral lines are studied. (25 refs).