A 154-day periodicity in the occurrence of hard solar flares?

  title={A 154-day periodicity in the occurrence of hard solar flares?},
  author={Erich Rieger and Gerald Harvey Share and David J. Forrest and Gottfried Kanbach and Claus Reppin and Edward L. Chupp},
Since the launch of the Solar Maximum Mission (SMM) satellite on 1980 February 14, the Gamma-Ray Spectrometer (GRS)1 has been monitoring the Sun in the energy range 0.3–100 MeV. Because of its large geometric area and good spectral resolution, the GRS has provided unprecedented spectral and temporal information about solar flares, of which 139 have been monitored. We report here on an analysis of the temporal distribution of these high-energy events to provide information on solar activity and… 
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