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    Extragalactic

    Active Galactic Nuclei

    X-ray observations by EXOSAT shed new light on the compact
    but intensely powerful sources at the heart of Active Galactic
    Nuclei, such as the optically violent variable AGN ON 325

    Prior to EXOSAT, AGN were not thought to show rapid variability. EXOSAT "long look" observations showed varibility down to timescales of ~ 1000 seconds.

    This placed stringent constraints on the size of the emitting region, which could not be much larger than the inner solar system (~ 500 000 000 km).

    Iron Lines

    The improved spectral resolution of the GSPC
    compared to previous detectors led to
    advances in the study of iron-emission features
    in the spectra of many classes of object, such
    as the AGN NGC1275


    Last Update: 08 Jul 2003

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