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The Seyfert Galaxy NGC 6814 -- a highly variable X-ray source

Michael Koenig·Susanne Friedrich·Ruediger Staubert·Jens Timmer
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Abstract

The Seyfert galaxy NGC 6814 is a highly variable X-ray source despite the fact that it has recently been shown not to be the source of periodic variability. The 1.5 year monitoring by ROSAT has revealed a long term downward trend of the X-ray flux and an episode of high and rapidly varying flux (e.g. by a factor of about 3 in 8 hours) during the October 1992 PSPC observation. Temporal analysis of this data using both Fourier and autoregressive techniques have shown that the variability timescales are larger than a few hundred seconds. The behavior at higher frequencies can be described by white noise.

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Michael Koenig, Susanne Friedrich, Ruediger Staubert, Jens Timmer. 1996-12-18. The Seyfert Galaxy NGC 6814 -- a highly variable X-ray source. https://arxiv.org/abs/astro-ph/9612176

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