[vsnet-grb-info 6559] GRB 080830: Fermi Gamma-ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8167
SUBJECT: GRB 080830: Fermi Gamma-ray Burst Monitor detection
DATE:    08/09/02 16:21:34 GMT
FROM:    Sheila McBreen at MPE  <smcbreen at mpe.mpg.de>

S. McBreen, E. Bissaldi and A. von Kienlin (MPE)  report on behalf
of the Fermi Gamma-ray Burst Monitor Team:

"At 08:50:16 UT on 30 August 2008, the Fermi Gamma-ray Burst
Monitor (GBM) triggered and located GRB 080830 (trigger 241779017
/080830.368). The on-ground calculated location, using the GBM
trigger data, is RA = 158.2, Dec = +33.6 (J2000 degrees)
(equivalent to J2000 10h 33m, +33d 36'), with an uncertainty
of 4.0 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 Fermi LAT
boresight is 23 degrees.

This event comprises four pulses beginning at T0-3 sec. The
main emission occurs during the first 20 sec and T90 (50-300 keV)
about is 45 sec. The time-averaged spectrum from T-3 to T+28 sec
is adequately fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.88 +/-0.12 and
the cutoff energy, parameterized as Epeak, is 280 +/-63 keV.

A slightly better fit is obtained with the Band function with the 
following parameters: alpha = -0.59 +/- 0.28, Epeak = 154 +/-57 keV
and beta = -1.69 +/- 0.16.

The fluence (50-300 keV) over T90 is 4.6E-06 ergs/cm2.

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