[vsnet-grb-info 6598] GRB 080905A: Fermi Gamma-ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8204
SUBJECT: GRB 080905A: Fermi Gamma-ray Burst Monitor detection
DATE:    08/09/09 12:03:02 GMT
FROM:    Elisabetta Bissaldi at MPE  <ebs at mpe.mpg.de>

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



"At 11:58:55 UT on 5 September 2008, the Fermi GBM triggered 
and located GRB 080905A (trigger 242308736 / 080905499), which was 
also detected by Swift (Pagani et al., GCN 8180). The on-ground 
calculated location, using the Fermi GBM trigger data, is 
RA = 286.3, Dec = -18.2 (J2000 degrees) (equivalent to J2000 
19h 05m, -18d 12'), with a statistical uncertainty of 4.6 degree 
(radius, 1-sigma containment; there is additionally a systematic 
error which is currently estimated to be 2 to 3 degrees). 
This position is 1.5 deg from the Swift refined position
(Evans et al., GCN 8203). The angle from the Fermi LAT boresight 
to the Swift position is 28 degrees.

This short GRB consists of two peaks, the first from T0 to
T0+0.4 sec and the second from T0+0.6 sec to T0+1.1 sec.
The first peak shows substructure in agreement with 
the Swift-BAT refined analysis (J. Cummings et al., GCN 8187).
T90 (50-300 keV) is about 1 sec.

The time-averaged spectrum from T0 to T0+1 sec is well fit 
by a power law function with index -0.96 +/- 0.05.
The fluence (50-300 keV) is 2.8(+/-0.2)E-07 erg/cm2
and the peak flux (50-300 keV) is 6.1 +/- 0.8 ph/cm2/s.


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