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1991 June 13 (M5.4)

A GOES M5.4 solar flare occurred on 1991 June 13 at an H-alpha location of N31W55 (heliographic coordinates). The soft X-ray flux began at 17:37 (63420 s), peaked at 18:04 (65040 s) and ended at 18:28 (66480 s) UT (GOES Geophysical Data Website). OSSE received a BATSE transient trigger at 64808 s but the four OSSE detectors were already pointed at 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 200 keV was observed during a ~210 s time interval (64760-64970 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 -6.3 was used to fit the data. The total fluence above 50 keV was 214.7 +/- 2.3 photons cm-2.

Figure 1

Figure 2

Last revised: 29 Jul 1999