Abstract Fourier analysis of an EXOSAT (ME) 30000 s observation of the Seyfert 1 galaxy NGC 4151 revealed a transient periodical phenomenon (period 131 ± 1 s and duration of a few thousand seconds) with a probability of a chance occurrence of the peak in the power spectrum of 2 10−3. Analysis of short data segments provides further evidence of this periodicity and indicates that the energy spectrum of this component becomes softer during the phenomenon. A careful analysis of possible instrumental effects does not appear to offer an explanation of the observed phenomenon.


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    Title :

    Detection of transient periodicity in an EXOSAT observation of NGC4151


    Contributors:
    Fiore, F. (author) / Massaro, E. (author) / Perola, G.C. (author) / Piro, L. (author)

    Published in:

    Publication date :

    1988-01-01


    Size :

    4 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



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