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Broadband Optical and Infrared Observations of Seyfert Galaxies

Penston, M. V. and Penston, Margaret J. and Selmes, R. A. and Becklin, E. E. and Neugebauer, G. (1974) Broadband Optical and Infrared Observations of Seyfert Galaxies. Monthly Notices of the Royal Astronomical Society, 169 (2). pp. 357-393. ISSN 0035-8711. doi:10.1093/mnras/169.2.357.

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Broadband observations between 0.3 and 3.4 μ are reported for II bright Seyfert galaxies. The ultraviolet and two micron fluxes of NGC 4151 have both increased by ∼ 0.3 mag between 1970 and 1971. 3C 120 was constant to within about ± 0.1 mag in the infrared during a period when it varied in the optical by ∼ 0.8 mag. Comparison with published data suggests NGC 4051 is an optical variable. The spatial distribution of the emitted flux shortward of 2.2 μ suggests that the emission from Seyfert galaxies can be decomposed into a nuclear source showing ultraviolet and infrared excesses and an extended source with normal starlike colours. The U–B and B–V colours fall on the two-colour diagram in positions consistent with a mixture of light from sources with galaxy-like and quasar-like colours and can be used to derive the ratio of the light from the nuclear source to that from the surrounding galaxy. This ratio is used to separate the contributions of nuclear source and galaxy in the infrared. The infrared spectrum of the nuclear source in NGC 1068 is steeper than that in the other Seyfert galaxies and more closely resembles that of non-Seyfert infrared galaxies such as M82 and NGC 253 rather than that of quasars. A wide range exists in the proportion of blue light contributed by the nuclear sources but the (B–[2.2 μ])₀ colours of the combined emission range only by ± 0.3 mag implying large differences exist in the (B–[2.2 μ])₀ of the nuclear source alone, in contrast to the homogeneity of the purely optical colours.

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Additional Information:© 1974 Royal Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1974 March 4; Published: 01 November 1974. We should like to thank all those who have given us assistance at the telescope and help in preparing the equipment. One of us (MVP) was a Carnegie Fellow and another of us (MJP) a Guest Investigator at the Hale Observatories while most of these observations were made. This work was supported in part by NASA grant NGL-05-002-007. We acknowledge the Wise Observatory of Tel Aviv University and the Smithsonian Foundation Grant SFC-0-3005 for the use of their facilities at Mitzpeh Ramon. We are also grateful to the Hale Observatories and Royal Greenwich Observatory for a generous allocation of telescope time.
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Tel Aviv UniversityUNSPECIFIED
Smithsonian FoundationSFC-0-3005
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Record Number:CaltechAUTHORS:20200721-124536772
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Official Citation:M. V. Penston, Margaret J. Penston, R. A. Selmes, E. E. Becklin, G. Neugebauer, Broadband Optical and Infrared Observations of Seyfert Galaxies, Monthly Notices of the Royal Astronomical Society, Volume 169, Issue 2, November 1974, Pages 357–393,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104480
Deposited By: Tony Diaz
Deposited On:21 Jul 2020 20:01
Last Modified:16 Nov 2021 18:32

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