Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I. An 8 month campaign of monitoring NGC 5548 with IUE

• The authors present emission-line and ultraviolet continuum observations of a type I Seyfert galaxy in which the time resolution is adequate for describing the character of variability. Using the IUE satellite, the nucleus of NGC 5548 was observed every 4 days for a period of 8 months. Its mean properties-continuum shape, line ratios-are not unusual for type I Seyfert galaxies, but it was found to be strongly variable. The ultraviolet continuum flux and broad emission line fluxes varied significantly, going through three large maxima and three deep minima. The great majority of all variations were well resolved in time. The data lend qualitative support to the view that photoionization by the nuclear continuum is responsible for driving the emission lines

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

Experimental/ astronomical spectra

galactic nuclei

Seyfert galaxies

ultraviolet astronomical observations/ UV

spectra

AD 1988 12 14 to 1989 08 07

broad-line region

active galactic nuclei

NGC 5548

IUE

emission-line

continuum

type I Seyfert galaxy

fluxes

photoionization

117 to 330 nm/ A9850R Active and peculiar galaxies A9580M Space ultraviolet astronomical observations A9850G Radiation and spectra of galaxies/ wavelength 1.17E-07 to 3.3E-07 m

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