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1999 August 01 (C4.3)

A GOES C4.3 solar flare occurred on 1999 August 01 at an H-alpha location of S28W27 (heliographic coordinates). The soft X-ray flux began at 23:12 (83520 s), peaked at 23:14 (83580 s), and ended at 23:26 (84360 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE solar-flare trigger at 83512 s and the OSSE detectors slewed to the scan-angle position of the Sun. Two OSSE detectors were aimed directly at the sun while the other two initiated standard on-source-off-source viewing strategies.

Significant gamma-ray emission to ~200 keV was observed lasting until about 83550 s UT with one peak of emmision at ~83575 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 83475-83557 s UT (82 seconds). The electron bremsstrahlung component was well-fit with a simple power law having a spectral index of ~3.70. There was no evidence for nuclear lines.

Figure 1

Figure 2

Last revised: 11 Dec 1997