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1991 December 26 (M4.6)A GOES M4.6 solar flare occurred on 1991 December 26. The location of the flare on the Solar surface is not known due to lack of an accompanying H-alpha event. The soft X-ray flux began at 10:47 (38820 s), peaked at 10:50 (39000 s) and ended at 10:54 (39240 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 38857 s but did not respond because the four OSSE detectors were involved in a complicated chopping procedure to observe the Galactic center. Fortunately, one of the detectors happened to be pointed at the scan-angle position of the Sun for the duration of the flare, and significant data were recorded by this detector. Significant emission of up to about 300 keV was observed during a ~150 s time interval (38865-39015 s). Count rate time profiles in various energy windows at a temporal resolution of ~8 s are shown in Figure 1. A representative count spectrum is shown in Figure 2. A single power law with an index of about -3.8 was used to fit the data. The total fluence above 50 keV was 843 +/- 13 photons cm-2. |
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