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Date and Time of the Query: 2019-04-20 T07:21:20 PDT
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For refcode 2002ApJS..141...31E:
Retrieve 211 NED objects in this reference.
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NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2002ApJS..141...31E JHK' Imaging Photometry of Seyfert 1 Active Galactic Nuclei and Quasars. II. Observation of Long-Term Variability Keigo Enya, Yuzuru Yoshii, Yukiyasu Kobayashi, Takeo Minezaki, Masahiro Suganuma, Hiroyuki Tomita, and Bruce A. Peterson Received 2001 October 29; accepted 2002 February 5 ABSTRACT Observations of 226 AGNs in the near-infrared J, H, and K' bands are presented along with the analysis of the observations for variability. Our sample consists mainly of Seyfert 1 AGNs and QSOs. About a quarter of the objects in each category are radio loud. The AGNs in the entire sample have the redshifts spanning the range from z = 0 to 1, and the absolute magnitudes from M_B_ = -29 to -18. All the objects were observed twice, and their variability was measured by differential photometry. A reduction method of differential photometry, optimized to the analysis of extended images, has been developed. The systematic error in variability arising from AGNs of highly extended images is estimated to be less than 0.01 mag in each of the J, H, and K' bands. The systematic error arising from the flat-fielding is negligible for most AGNs, although it is more than 0.1 mag for some particular cases. The overall average flat-fielding error is 0.03 mag for the image pairs. We find that these systematic errors are superseded by statistical errors, and the overall average total systematic and statistical errors amounts to 0.05 mag in the measured variability in each band. We find that 58% of all the AGNs in the entire sample show variability of more than 2 {sigma}, and 44% of more than 3 {sigma}. This result holds independent of the J, H, and K' bands. The detection rate of variability is higher for a subsample of higher photometric accuracy, and there appears no limit to this tendency. In particular, when we consider a subsample with small photometric errors of {sigma} < 0.03 mag, the rate of 2 {sigma} detection is 80%, and 64% for 3 {sigma} detection. This suggests that most AGNs are variable in the near-infrared. Subject headings: galaxies: active - galaxies: photometry - galaxies: Seyfert - infrared: galaxies - quasars: general
Retrieve 211 NED objects in this reference.
Please click here for ADS abstract

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