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Session 11 - AGN.
Display session, Monday, January 13
Metropolitan Ballroom,

[11.01] Ultraviolet Variability in Active Galaxies: A Systematic Survey of the IUE Archives

R. Edelson (U. Iowa), S. Penton, J. M. Shull, T. Ayres (CASA, U. Colorado), G. Pike (NASA/GSFC)

Now that the mission of IUE has been completed, the Colorado IUEAGN group is using the TOMSIPS software to systematically re-extract all of the AGN data in the archives. The spectra are then fitted with a multi-parameter model in order to measure continuum and line fluxes. We then compile a database of fluxes in a number of bands for each observation.

In this talk, we present continuum variability data for all AGN with at least 12 SWP observations. These data are generally sensitive to long-term variations, as the IUE satellite was operational for almost 20 yr. For certain objects that were the subjects of intensive monitoring campaigns (e.g., NGC 5548, NGC 4151, etc.), shorter time scale data also exist.

We will report the results of a number of studies. First, for individual well-observed objects, we determine the relation between variability amplitude and wavelength, on both long and short time scales. Second, for entire classes of objects (e.g., Seyfert 1s or BL Lacs), we measure the correlation between mean object luminosity and variability amplitude. Finally, we compare the variability properties of different classes of objects.

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Program listing for Monday