We present a study of the intrinsic UV absorption and emission lines in an historically low-state spectrum of the Seyfert 1 galaxy NGC 5548 , which we obtained in 2004 February at high spatial and spectral resolution with the Space Telescope Imaging Spectrograph ( STIS ) on the Hubble Space Telescope ( HST ) .
We isolate a component of emission with a width of 680 km s ^ { -1 } ( FWHM ) that arises from an “ intermediate line region ” ( ILR ) , similar to the one we discovered in NGC 4151 , at a distance of \sim 1 pc from the central continuum source .
From a detailed analysis of the five intrinsic absorption components in NGC 5548 and their behavior over a span of 8 years , we present evidence that most of the UV absorbers only partially cover the ILR and do not cover an extended region of UV continuum emission , most likely from hot stars in the circumnuclear region .
We also find that four of the UV absorbers are at much greater distances ( > 70 pc ) than the ILR , and none have sufficient N V or C IV column densities to be the ILR in absorption .
At least a portion of the UV absorption component 3 , at a radial velocity of - 530 km s ^ { -1 } , is likely responsible for most of the X-ray absorption , at a distance < 7 pc from the central source .
The fact that we see the ILR in absorption in NGC 4151 and not in NGC 5548 suggests that the ILR is located at a relatively large polar angle ( \sim 45 ^ { o } ) with respect to the narrow-line region outflow axis .