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1999 November 21 (M3.4)

A GOES M3.4 solar flare occurred on 1999 November 21 at an H-alpha location of S15E56 (heliographic coordinates). The soft X-ray flux began at 18:10 (65400 s), peaked at 18:20 (66000 s) and ended at 18:25 (66300 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 65616 s and the four OSSE detectors slewed to the scan-angle position of the Sun. Detectors 3 and 4 initiated +/- 4.5 degree on-source-off-source viewing strategies while detectors 1 and 2 remained pointed at the Sun. The detector orientation required to view the Sun was such that detectors 1 and 2 were partially obscured by detectors 3 and 4. Because the resulting attenuation is poorly known, only data from the unobscured detectors 3 and 4 are used here.

Four peaks of emmission up to about 250 keV were observed during an ~600 s time interval (65684-66290 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 -4.98 +/- 0.03 fit the data. The total fluence above 50 keV was 454 +/- 6 photons cm-2.

Figure 1

Figure 2

Last revised: 26 Jul 1999