Abstract
A ∼7 hour observation of the central part of the Coma Cluster of galaxies has been performed with the EXOSAT LE telescopes and CMA detectors. Five serendipitous sources are detected within the inner 35 arcmin radius of the field. Optical spectroscopy demonstrates that at least three of these are background AGN not associated with the cluster. At the sensitivity level of the EXOSAT exposure, we would have expected to see only 0.01 background sources based on the Einstein Medium Sensitivity Survey. The EXOSAT and Einstein results may be reconciled if these AGN have a much softer average X-ray spectrum than previously assumed.
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Bond, H.E. and Sargent, W.L.W. Ap. J. (Letters), 185, L109 (1973).
Branduardi-Raymont, G. et al. Advances in Space Research, Pergamon Press, in press (1984).
Burstein, D. and Heiles, C. Astron. J., 87, No. 8, 1165 (1982).
de Korte, P.A.J. et al. Space Science Reviews, 30, 495 (1981).
Gioia, I.M. et al. Ap. J., 283, 495 (1984).
Helfand, D.J., Ku, W.H.-M. and Abramopoulos, F. Highlights of Astronomy, P.A.Wayman ed., Vol.5, 747 (1980).
Hewitt, A. and Burbidge, G. Ap. J. Supp. Ser., 43, 57 (1980).
Ku, W.H.M., Helfand, D.J. and Lucy, L.B. Nature, 288, 323 (1980).
Reichert, G.A., Mason, K.O., Thorstensen, J.R. and Bowyer, S. Ap. J., 260, 437 (1982).
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Branduardi-Raymont, G., Mason, K.O., Murdin, P.G. et al. Optical observations of serendipitous EXOSAT sources in the Coma Cluster. Space Sci Rev 40, 647–652 (1985). https://doi.org/10.1007/BF00179882
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DOI: https://doi.org/10.1007/BF00179882