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1991 June 02 (M5.2)
A GOES M5.2 solar flare occurred on 1991 June 02. 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 07:37 (27420 s), peaked at 07:46 (27960 s) and ended at 09:37 (34620 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 27633 s and the four OSSE detectors slewed to the scan-angle position of the Sun. Two of the four detectors then initiated +/- 4.5 degree on-source-off-source viewing strategies while the other two detectors remained pointed at the Sun.
Significant emission of up to about 300 keV was observed during a ~180 s time interval (27680-27860 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 broken power law which hardened from an index of about -5.7 below a break energy of ~145 keV to about -3.1 above the break energy fit the data better than a single power law. The total fluence above 50 keV was 252.4 +/- 2.2 photons cm-2.
 Figure 1 |
 Figure 2 |