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1991 October 21 (C2.9)

A GOES C2.9 solar flare occurred on 1991 October 21 at an H-alpha location of S14E89 (heliographic coordinates). The soft X-ray flux began at 20:36 (74160 s), peaked at 20:41 (74460 s) and ended at 21:17 (76620 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 74187 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.

Significant emmission of up to about 200 keV was observed during a ~80 s time interval (74200-74280 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 -5.1 was used to fit the data. The total fluence above 50 keV was 29.8 +/- 0.9 photons cm-2.

Figure 1

Figure 2

Last revised: 14 Jul 1999