OSSE SOLAR FLARE OBSERVATIONS     


This web site provides preliminary gamma-ray data for solar flares observed by OSSE. OSSE solar-flare observations typically are accomplished via dedicated observations of the Sun during periods of high solar activity or via solar-flare triggers provided by BATSE when the Sun is sufficiently near the OSSE scan plane. In response to a BATSE flare trigger, the OSSE detectors slew to the position of the Sun and initiate observations. Flares can also be observed when the Sun is off-axis if the flare is sufficiently intense.

Detected flares are listed in the following table by date, approximate peak emission time (UT), and GOES X-ray classification. Preliminary fluences (time-integrated fluxes) are provided where emission is observed. Listed are (1) >50 keV fluence of the electron bremsstrahlung power law, (2) >300 keV fluence of the power law, (3) summed fluence in narrow nuclear lines greater than 1 MeV, (4) fluence in the 2.223 MeV neutron-capture line, and (5) fluence above 16 MeV. All fluences are photons cm-2. Because of earth occultation or missing data, some fluences are not accumulated over the entire flare.

Clicking on a flare date will open a page containing a brief description of the flare and the OSSE observations along with a plot of count-rate time profiles in various energy bands and a plot of the observed count spectrum. The time profiles are for the following energy windows: 0.05 - 0.1, 0.1 - 0.3, 0.3 - 0.8, 0.8 - 1.5, 1.5 - 3.0, 3.0 - 10.0, and >16 MeV. The total shield count rate is also shown which corresponds to emission above ~150 keV. (Note: The lowest-energy profile may not accurately represent the true profile since no attempt to correct for possible wrapping of the PHA channels has been made.) Clicking on either plot will download a PostScript version.

We emphasize that these data are preliminary. For most of the flares listed here, the subtracted background was derived using data obtained during 60-sec intervals prior to and after the flare interval. For long-duration flares occurring when the background is rapidly changing, this can result in spurious high-energy continuum.

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Date
Time (UT)
GOES Class
>50 keV
>300 keV
Narrow Lines >1 MeV
2.223 MeV
>16 MeV
01-May-2000 10:21 M1.1 524+/-5 5.7+/-0.2      
08-Apr-2000 20:45 M1.8 32.9+/-.75 0.09+/-0.01      
04-Apr-2000 15:23 C9.7 450+/-9 8.7+/-0.2      
24-Mar-2000 7:45 X1.8 1990+/-120(4) 290+/-40 5.8+/-1.2 <1.5gamma rays
05-Feb-2000 19:27 X1.2       <2.2  
04-Feb-2000 9:15 M3.0 29.3+/-0.7 4.6+/-0.1   <0.3  
20-Jan-2000 2:24 C4.1 86+/-1 3.2+/-0.1   <0.4  
12-Jan-2000 1:36 M2.8 2145+/-25        
02-Jan-2000 22:23 C5.1 171.6+/-2.5 1.30+/-.02      
16-Dec-1999 7:36 C2.4 51.8+/-1.8 1.26+/-.04      
03-Dec-1999 19:52 C6.3 13.6+/-.9 .55+/-.04      
22-Nov-1999 2:55 C2.9 54.7+/-.7 .16+/-.01      
21-Nov-1999 18:15 M3.4 454+/-6        
20-Nov-1999 22:31 M3.2 151+/-3        
16-Nov-1999 6:06 M2.3 154.3+/-4.8 .14+/-.01      
17-Sep-1999 1:18 M2.1 260+/-3        
08-Sep-1999 12:18 M1.4 514+/-8 11.7+/-.2      
28-Aug-1999 17:58 X1.1 4350+/-50        
28-Aug-1999 00:53 M2.8 315+/-28 1.31+/-.11      
03-Aug-1999 6:29   6.0+/-1.8 1.14+/-0.34      
02-Aug-1999 21:23 X1.4 3230+/-65 10.5+/-0.7      
02-Aug-1999 14:45 C6.9 116.5+/-1.5 .089+/-.001      
02-Aug-1999 11:49 C6.3 88.6+/-1.4 .28+/-.01      
01-Aug-1999 23:11 C4.3 29.9+/-1.3 .24+/-.01      
30-Jul-1999 16:05 C6.1 27.5+/-.9 .035+/-.001      
29-Jul-1999 19:34 M5.1 174.2+/-1.8 .075+/-.001      
23-Jul-1999 15:57 M1.0 31.6+/-3.4        
10-May-1999 5:27 M2.5 310.7+/-6.6 2.2+/-0.1      
09-May-1999 17:58 M7.6 1981+/-10 2.1+/-0.1      
29-Apr-1999 19:51 M1.1 29.8+/-1.2        
22-Nov-1998 6:39 X3.7 (1) (1)     gamma rays
18-Aug-1998 22:16 X4.9 1830+/-21(2) 70+/-4(2)      
29-May-1998 00:56 M6.7 916+/-15 13+/-1.5      
08-May-1998 01:57 M3.1 398+/-4        
01-Dec-1997 13:27 C6.6 <1        
01-Dec-1997 2:34 M1.2 48.0+/-1.6        
28-Nov-1997 5:02 M6.8 165.1+/-6.3        
27-Nov-1997 16:13 C3.8 125.6+/-2.0        
27-Nov-1997 13:15 X2.6 680+/-34 25.2+/-4.1 1.2+/-0.6 1.2+/-0.3  
26-Nov-1997 18:32 M2.0 20.6+/-1.2        
17-Nov-1997 15:05 C8.6 47.4+/-3.4        
06-Nov-1997 11:56 X9.4 (3) (3) (3) (3) neutrons
27-Dec-1991 11:08 M1.3 524.9+/-9.3        
26-Dec-1991 10:48 M4.6 843+/-13        
25-Dec-1991 12:55 M1.4 258.6+/-5.8        
16-Dec-1991 01:02 C7.5 119.2+/-2.5        
15-Dec-1991 13:56 C6.0 207.0+/-2.0 2.2+/-0.1      
14-Dec-1991 14:50 M1.6 303.9+/-5.2 2.4+/-0.1      
13-Dec-1991 03:54 M2.9 441.8+/-6.8        
15-Nov-1991 22:37 X1.5 (1) (1) 7.1 +/- 1.9 7.7 +/- 1.1  
13-Nov-1991 21:16 M1.3 415.7+/-5.6        
11-Nov-1991 16:38 C5.9 199.5+/-6.4        
10-Nov-1991 20:09 M7.9 3876+/-19 27.3+/-0.3      
10-Nov-1991 01:28 M6.9 1604+/-13 10.0+/-0.2      
09-Nov-1991 20:52 M1.4 779.6+/-9.1 11.7+/-0.2      
08-Nov-1991 17:04 M4.2 64.3+/-4.5        
30-Oct-1991 19:15 M4.3 403.6+/-6.4        
27-Oct-1991 5:42 X6.1 (1) (1) 63+/-3 141+/-3 neutrons
24-Oct-1991 2:38 X2.1 (1) (1) 5.7+/-1.2 7.3+/-1.0  
21-Oct-1991 20:37 C2.9 29.8+/-0.9        
12-Oct-1991 05:06 C9.2 34.1+/-1.0        
30-Jun-1991 2:56 M5.0 (1) (1) 2.8+/-0.9   gamma rays
13-Jun-1991 18:00 M5.4 214.7+/-2.3        
10-Jun-1991 21:27 C8.7 206.6+/-5.0        
10-Jun-1991 16:54 M3.2 1162+/-19 3.1+/-0.1      
10-Jun-1991 11:01 M1.2 85.0+/-2.0        
10-Jun-1991 02:29 M4.5 761.5+/-3.8 2.1+/-0.1      
09-Jun-1991 13:07 M1.2 125.4+/-1.5        
08-Jun-1991 04:13 C2.6 9.0+/-0.8        
07-Jun-1991 06:14 M1.3 34.4+/-1.6        
06-Jun-1991 07:05 M1.2 141.9+/-2.9        
05-Jun-1991 23:30 C3.7 24.8+/-2.5        
05-Jun-1991 00:01 M1.4 175.8+/-1.4        
04-Jun-1991 3:41 X12+ (1) (1) 831+/-24 1050+/-19 gamma rays and neutrons
03-Jun-1991 20:58 M1.5 155.4+/-3.4        
02-Jun-1991 07:42 M5.2 252.4+/-2.2        
01-Jun-1991 15:05 X12+ (3) (3) (3) (3) neutrons

(1) These quantities are not determined because the Sun was off-axis and the fit was performed only on >1 MeV data.

(2) The fluences reported are not accumulated over the entire flare due to either occultation of the Sun or missing data. (3) Data not available due to SAA passage.

(4) Fluence >100 keV


List of Recent OSSE Publications
Recent publications are available in PostScript and Adobe Acrobat format. You may view the abstract for each paper by clicking on its title. The complete paper can be obtained by following the desired link to the right of each paper.
  1  "Accelerated Particle Composition and Energetics and Ambient Abundances from Gamma-Ray Spectroscopy of the 1991 June 4 Solar Flare"
R.J. Murphy, et al., Ap. J., 490, 883 (1997)
PS PDF
  2  "Surprisingly Intense Neutron Emission from a Flare Behind the Limb of the Sun"
R.J. Murphy, G. H. Share, K. W. DelSignore and X.-M. Hua, Ap. J., 510, 1011 (1999)
PS PDF
  3  "Accelerated-Particle Spectral Variability in the 1991 June 11 Solar Flare"
R.J. Murphy and G. H. Share, Fifth CGRO Symposium, Portsmouth, AIP, 510, 559 (2000)
PS PDF
  4  "Atmospheric Gamma-Ray Lines Produced by Cosmic Rays and Solar Energetic Particles"
G. H. Share, and R.J. Murphy, Proc. 26th ICRC, Salt Lake City, SH 3.6.06 (1999)
PS PDF
  5  "Gamma-Ray Measurement of Energetic Heavy Ions at the Sun"
G. H. Share and R.J. Murphy, Proc. 26th ICRC, Salt Lake City, SH 1.2.05 (1999)
PS PDF
  6  "Simultaneous Observations of Solar Flares with CGRO/OSSE and Yohkoh/WBS"
R.J. Murphy, G. H. Share and M. Yoshimori, in High Energy Solar Physics: Anticipating HESSI, eds. R.Ramaty and N. Mandzhavidze, ASP Conference Series Vol. 206, 387 (2000)
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  7  "Gamma Ray Spectroscopy in the Pre-HESSI Era"
G. H. Share and R.J. Murphy, in High Energy Solar Physics: Anticipating HESSI, eds. R.Ramaty and N. Mandzhavidze, ASP Conference Series Vol. 206, 377 (2000)
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  7  "Limits on Radiative Capture Gamma-Ray Lines and Implications for Energy Content in Flare-Accelerated Protons"
G. H. Share, R.J. Murphy and E. K. Newton, accepted for publication in Solar Physics Reviews (2001)
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  7  "Correlation of Upper-Atmospheric 7Be with Solar Energetic Particle Events"
G. W. Phillips, G. H. Share, S. E. King, R. A. August, A. J. Tylka, J. H. Adams Jr., M. I. Panasyuk, R. A. Nymmik, B. M. Kuzhevskij, V. S. Kulikauskas, D. A. Zhuravlev, A. R. Smith, D. L. Hurley, R. J. McDonald, Geophys. Res. Lett. Vol. 28 , No. 5 , p. 939 (2001)
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  7  "Gamma-Ray Line Observations of the 2000 July 14 Flare and SEP Impact on the Earth"
G.H. Share, R.J. Murphy, A.J. Tylka, R.A. Schwartz, M. Yoshimori, K. Suga, S. Nakayama, H. Takeda, submitted for publication in Solar Physics (2001)
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