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1999 November 20 (M3.2)

A GOES M3.2 solar flare occurred on 1999 November 20 at an H-alpha location of S15E19 (heliographic coordinates). The soft X-ray flux began at 22:17 (80220 s), peaked at 22:35 (81300 s) and ended at 22:51 (82260 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 80813 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.

Significant emmission of up to about 200 keV was observed during an ~500 s time interval (80842-81342 s). Flare emission may have continued beyond this time but no OSSE data were available due to a TDRSS satellite outage. 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 -5.01 +/- 0.06 fit the data. The total fluence above 50 keV was 151 +/- 3 photons cm-2.

Figure 1

Figure 2

Last revised: 26 Jul 1999