[vsnet-grb-info 6503] GLAST Burst Monitor detection of a GRB: 080816B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8111
SUBJECT: GLAST Burst Monitor detection of a GRB: 080816B
DATE:    08/08/21 22:31:00 GMT
FROM:    Rob Preece at UAH  <Rob.Preece at nasa.gov>

R. D. Preece (UAHuntsville) and A.J. van der Horst (NASA/ORAU) report  
on behalf of the GLAST Burst Monitor Team:

"At 23:44:01 UT on 16 August, 2008, the GLAST Burst Monitor (GBM)
triggered and located GRB 080816B (trigger 240623035 / 080816.989).
The on-ground calculated location, using the GBM trigger data, is
RA = 288.5, Dec = -6.5 (J2000 degrees)
(equivalent to J2000 19h 14m, -06d 30'),
with an uncertainty of 5.2 degrees (radius, 1-sigma containment,  
statistical only; there is additionally a systematic error which is  
currently estimated to be 2 to 3 degrees). The angle from the Large  
Area Telescope (LAT) boresight is 70 degrees.

This GRB was about 5 s long with 2 peaks, showing structure on the 64  
ms time scale. The time-averaged spectrum from T-3.584 to T+1.536 s,  
in the energy range 6 keV to 3500 keV, is best fit with a power law  
times exponential cutoff. The power law index is -0.37 +/- 0.17 and  
the cutoff energy, parameterized as Epeak, is 1230 +/- 230 keV. We  
note that this is a hard event. The average photon flux is 1.38 +/-  
0.08 ph/s-cm^2 in the energy interval 25 - 1000 keV.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."