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1999 November 16 (M2.3)

A GOES M2.3 solar flare occurred on November 16 1999 at an H-alpha location of S14E10 (heliographic coordinates). The soft X-ray flux began at 6:06 (21960 s), peaked at 7:10 (25800 s), and ended at 7:39 (27540 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE solar-flare trigger at 21954 s and the four OSSE detectors slewed to the scan-angle position of the Sun and initiated standard on-source-off-source viewing strategies. Solar observations began at 21960 s UT.

Significant gamma-ray emission to ~150 keV was observed lasting until about 22150 s UT with one peak of emission at ~22100 s. There was also a smaller amount of gamma-ray emission lasting until ~22300 s. The secondary emissions were not included in the count spectrum. Count rate time profiles in various energy windows at a temporal resolution of ~8 s are shown in Figure 1. Figure 2 shows a representative count spectrum obtained from one Sun-pointed detector integrated over the time period 21972-22251 s UT (279 seconds). The electron bremsstrahlung component was well-fit with a simple power law having a spectral index of ~4.91. There was no evidence for nuclear lines.

Figure 1

Figure 2

Last revised: 12 July 2000