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Ariel V and Copernicus measurements of the X-ray variability of Cyg X-1

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Abstract

THE collimated proportional counter (experiment C of MSSL) on Ariel V viewed Cyg X-1 in 1975 from May 3 1400 UT until May 15 1000 UT. We report here observations of the intensity and spectrum obtained with an integration time of ∼30 min. They show that, at the beginning of this period, Cyg X-1 was more intense, had a steeper spectrum and was generally more active than has been observed during the past 2½yr by Copernicus1,2. Towards the end of the period the source seemed to be returning to its lower state.

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Authors and Affiliations

  1. Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey, UK

    P. W. SANFORD, J. C. IVES, S. J. BELL BURNELL & K. O. MASON

  2. Royal Greenwich Observatory, Herstmonceux Castle, Hailsham, E. Sussex, BN27 1RP, UK

    P. MURDIN

Authors
  1. P. W. SANFORD
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  2. J. C. IVES
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  3. S. J. BELL BURNELL
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  4. K. O. MASON
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  5. P. MURDIN
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SANFORD, P., IVES, J., BURNELL, S. et al. Ariel V and Copernicus measurements of the X-ray variability of Cyg X-1. Nature 256, 109–111 (1975). https://doi.org/10.1038/256109a0

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  • DOI: https://doi.org/10.1038/256109a0

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