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1999 December 16 (C2.4)

A GOES C2.4 solar flare occurred on December 16 1999 at an H-alpha location of S13E46 (heliographic coordinates). The soft X-ray flux began at 7:23 (26580 s), peaked at 7:23 (26580 s), and ended at 7:39 (27540 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE solar-flare trigger at 27400 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 27420 s UT. There was a small data gap at the beginning of the flare.

Significant gamma-ray emission to ~200 keV was observed lasting until about 27555 s UT with one peak of emission at ~27450 s. 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 27418-27557 s UT (139 seconds). The electron bremsstrahlung component was well-fit with a simple power law having a spectral index of ~3.07. There was no evidence for nuclear lines.

Figure 1

Figure 2

Last revised: 12 July 2000