EDP Sciences
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Volume 369, Number 2, April II 2001
Page(s) 450 - 458
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010117

A&A 369, 450-458 (2001)
DOI: 10.1051/0004-6361:20010117

RX J2217.9-5941: A highly X-ray variable Narrow-Line Seyfert1 galaxy

D. Grupe1, H.-C. Thomas2 and K. M. Leighly3, 4

1  MPI für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
2  MPI für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany
3  Columbia Astrophysics Laboratory, 538 West 120th St., New York, NY 10027, USA
4  Dept. of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019, USA

(Received 26 October 2000 / Accepted 12 January 2001 )

We report the discovery of a highly X-ray variable AGN, RX J2217.9-5941. This object was bright during the ROSAT All-Sky Survey (RASS), during which a decrease in the count rate by a factor of 12 was observed. It was found to be much fainter in follow-up HRI observations and is therefore an X-ray transient AGN candidate. On long time scales of years, its count rate decreased by a factor of about 30 between the RASS and the ROSAT HRI and ASCA observations in 1998. Analysis of the ASCA data, complicated by source confusion and poor statistics, tentatively indicates a steep spectrum in the faint state. There is no evidence for variability among 5 optical observations of the object obtained between 1992 and 1998. We discuss the variability of RX J2217.9-5941 and its possible X-ray transient nature.

Key words: accretion, accretion disks -- galaxies: active -- galaxies: nuclei -- galaxies: Seyfert -- galaxies: individual (RX J2217.9 -- 5941)

Offprint request: D. Grupe, dgrupe@xray.mpe.mpg.de

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