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1999 April 29 (M1.1)

A GOES M1.1 solar flare occurred on 1999 April 29 at an H-alpha location of N22W16 (heliographic coordinates). The soft X-ray flux began at 19:45 (71100 s), peaked at 19:54 (71640 s) and ended at 20:05 (72300 s) UT (GOES Geophysical Data Web Site). OSSE received a BATSE transient trigger at 71399 s and the four OSSE detectors slewed to the scan-angle position of the Sun and initiated +/- 4.5 degree on-source-off-source viewing strategies.

Significant emmission of up to about 200 keV was observed during a ~120 s time interval (71430-71550 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 about -4.7 was used to fit the data. The total fluence above 50 keV was 29.8 +/- 1.2 photons cm-2.

Figure 1

Figure 2

Last revised: 20 Jul 1999