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Title:
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
Authors:
Clavel, J.; Reichert, G. A.; Alloin, D.; Crenshaw, D. M.; Kriss, G.; Krolik, J. H.; Malkan, M. A.; Netzer, H.; Peterson, B. M.; Wamsteker, W.; Altamore, A.; Baribaud, T.; Barr, P.; Beck, S.; Binette, L.; Bromage, G. E.; Brosch, N.; Diaz, A. I.; Filippenko, A. V.; Fricke, K.; Gaskell, C. M.; Giommi, P.; Glass, I. S.; Gondhalekar, P.; Hackney, R. L.; Halpern, J. P.; Hutter, D. J.; Joersaeter, S.; Kinney, A. L.; Kollatschny, W.; Koratkar, A.; Korista, K. T.; Laor, A.; Lasota, J.-P.; Leibowitz, E.; Maoz, D.; Martin, P. G.; Mazeh, T.; Meurs, E. J. A.; Nair, A. D.; O'Brien, P.; Pelat, D.; Perez, E.; Perola, G. C.; Ptak, R. L.; Rodriguez-Pascual, P.; Rosenblatt, E. I.; Sadun, A. C.; Santos-Lleo, M.; Shaw, R. A.; Smith, P. S.; Stirpe, G. M.; Stoner, R.; Sun, W. H.; Ulrich, M.-H.; van Groningen, E.; Zheng, W.
Affiliation:
AA(IUE Observatory, Madrid, Spain), AB(IUE Observatory, Madrid, Spain), AC(NASA, Goddard Space Flight Center; Computer Sciences Corp., Greenbelt, MD), AD(NASA, Goddard Space Flight Center; Computer Sciences Corp., Greenbelt, MD), AE(Paris, Observatoire, Meudon, France)
Publication:
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 366, Jan. 1, 1991, p. 64-81. (ApJ Homepage)
Publication Date:
01/1991
Category:
Astrophysics
Origin:
STI
NASA/STI Keywords:
ACTIVE GALACTIC NUCLEI, ASTRONOMICAL SPECTROSCOPY, GALACTIC STRUCTURE, IUE, SEYFERT GALAXIES, EMISSION SPECTRA, TIME SERIES ANALYSIS, ULTRAVIOLET SPECTRA, VARIABILITY
DOI:
10.1086/169540
Bibliographic Code:
1991ApJ...366...64C

Abstract

Emission-line and UV continuum observations of the type I Seyfert galaxy NGC 5548 were carried out for a period of 8 months with the IUE satellite. It was found that both the continuum shape and the line ratios of NGC 5548, while being not unusual for type I Seyfert galaxies, are strongly variable. The UV continuum flux and broad emission line fluxed went through three large maxima and three deep minima; the ratio of miximum to minimum flux was about 4.5 for the continuum at 1350 A. The N V and the He II emission lines exhibited maximum-to-minimum flux ratios as high as those of the continuum; other ionization lines (Ly-alpha, C IV, and C III) exhibited smaller amplitude fluctuations, with the smallest being recorded for the Mg II line (about 1.3). It was found that, except for Mg II, the emission-line variations correlated extremely well with those of the 1350-A continuum.

Associated Articles

Part 1     Part  2     Part  3     Part  4     Part  5     Part  6     Part  7     Part  8     Part  9     Part 10     Part 11     Part 14     Part 13     Part 12     Part 15    


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