[vsnet-grb-info 6599] GRB 080905B: Fermi Gamma-ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8205
SUBJECT: GRB 080905B: Fermi Gamma-ray Burst Monitor detection
DATE:    08/09/09 18:15:32 GMT
FROM:    Narayana Bhat at U Alabama/Huntsville/GBM  <Narayana.Bhat at nasa.gov>

P. N. Bhat (UAH), W. Paciesas (UAH) and A.J. van der Horst (NASA/ORAU)
report on behalf of the Fermi Gamma-ray Burst Monitor Team:


"At 16:55:46 UT on 5 September 2008, the Fermi GBM triggered
and located GRB 080905B (trigger 242326547 / 080905705), which was
also detected by Swift (Stroh et al., GCN 8182). The on-ground calculated
location, using the Fermi GBM trigger data, is RA = 307.1, Dec = -60.2
(J2000 degrees) (equivalent to J2000 20h 28m, -60d 12'), with a statistical
uncertainty of 5.7 degree (radius, 1-sigma containment; there is
additionally a systematic error which is currently estimated to be 2 to 3
degrees). The angle from the Fermi LAT boresight to the GBM localization
is 82 degrees. 

This long GRB consists of one main peak at trigger time, possibly a weak
pre-trigger at T-20 s and second peak at T0 + 70 sec and the third from
T0+80 sec to T0+110 sec similar to the Swift light curve.

The burst duration (in the energy range 20-1000 keV) T90 is about 159 sec.

The time-averaged spectrum from T0-20 to T0+110 sec is well fit by a power
law function with index -1.75 +/- 0.12.The fluence (20-1000 keV) is
4.1(+/-0.3)E-08 erg/cm2and the peak flux (20-1000 keV) is 0.21 +/- 0.02
ph/cm2/s.

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