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1999 November 22 (C2.9)

A GOES C2.9 solar flare occurred on 1999 November 22. 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 2:53 (10380 s), peaked at 2:58 (10680 s), and ended at 3:04 (11040 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE solar-flare trigger at 10475 s. The OSSE detectors were already aimed at the sun and two detectors remained in the same position throughout the entire flare. The other two detectors performed a standard on-source-off-source viewing strategy.

Significant gamma-ray emission to 200 keV was observed lasting until about 10520 s UT with one peak of emission at ~10490 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 10450-10508 s UT (58 seconds).The electron bremsstrahlung component was well-fit with a simple power law having a spectral index of ~4.25. There was no evidence for nuclear lines.

Figure 1

Figure 2

Last revised: 11 Dec 1997