THE GALAXY COMPONENT AND NUCLEAR FLUX MEASUREMENTS OF NGC-5548 FROM DIRECT IMAGING

We present the results of analysis of direct imaging data of the galax y NGC 5548. This galaxy hosts a time-variable active nucleus which has been the focus of intensive spectroscopic monitoring. We focus here o n data obtainable from direct imaging of the object. First, we use an image modeling program to derive an image of the galaxy component alon e, with the AGN removed, and use such images to study the structure an d color of the galaxy. The host galaxy appears to be a relatively norm al bulge-dominated (Sa type) spiral, with no evidence of current star formation in the bulge. The derived ''AGN-free'' images are useful for deriving corrections for the galaxian light that is an inevitable con taminant in spectroscopic and photometric measurements of this object. We discuss how to measure the flux from the nucleus from direct image s, and in particular describe a method to obtain photometrically calib rated nuclear flux measurements from less than optimum images. We pres ent nuclear flux values from images contributed by the coauthors, and present flux measurements, corrected for host galaxy light, derived fr om published photoelectric aperture photometry. We discuss the contami nation of the standard spectroscopic aperture by galaxy light. The gal axy flux contamination in the standard spectroscopic aperture derived from the AGN-free images agrees extremely well with that derived from a totally independent spectroscopic method.