OSSE observations of NGC 4151

M. Maisack*, W. N. Johnson, R. L. Kinzer, M. S. Strickman, J. D. Kurfess, R. A. Cameron, G. V. Jung, D. A. Grabelsky, W. R. Purcell, M. P. Ulmer

*Corresponding author for this work

Research output: Contribution to journalArticle

63 Scopus citations


We report results of a 2 week observation of the Seyfert galaxy NGC 4151 with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory (GRO). The source had a very soft spectrum which is best represented by a broken power law or Sunyaev-Titarchuk thermal Comptonization model. It can be characterized by an exponential shape with an e-folding energy of 39 ± 2 keV in the energy range 65-300 keV, and an intensity at 100 keV of (2.33 ±0.05) × 10-5 photons cm-2 s-1 keV-1. Source intensity variability of ∼25% was observed during the 14 days of our observations; no significant change in spectral shape was detected for this period. The steepness and shape of the spectrum above 100 keV rule out (χ2 probability ∼7 × 10-4) simple pair cascade models in a compact source which have been suggested for Seyfert galaxies.

Original languageEnglish (US)
Pages (from-to)L61-L64
JournalAstrophysical Journal
Issue number2 PART II
StatePublished - Jan 1 1993


  • Galaxies: Seyfert
  • Galaxies: individual (NGC 4151)
  • Gamma rays: observations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Maisack, M., Johnson, W. N., Kinzer, R. L., Strickman, M. S., Kurfess, J. D., Cameron, R. A., Jung, G. V., Grabelsky, D. A., Purcell, W. R., & Ulmer, M. P. (1993). OSSE observations of NGC 4151. Astrophysical Journal, 407(2 PART II), L61-L64. https://doi.org/10.1086/186806