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1991 June 05 (M1.4)

A GOES M1.4 solar flare occurred on 1991 June 05. 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 23:48 (85680 s) on June 04, peaked at 00:04 (240 s) on June 05 and ended at 00:14 (840 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 22 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 emmission of up to about 500 keV was observed during a ~155 s time interval (15-170 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 -4.6 below a break energy of ~120 keV to about -3.4 above the break energy fit the data better than a single power law. The total fluence above 50 keV was 175.8 +/- 1.4 photons cm-2.

Figure 1

Figure 2

Last revised: 19 Jul 1999