[vsnet-grb-info 6893] GRB 081025: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8483
SUBJECT: GRB 081025: Fermi GBM observation
DATE:    08/11/05 17:11:18 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

A. von Kienlin (MPE) and E. Bissaldi (MPE)
report on behalf of the Fermi GBM Team: 

"At 08:23:05.29 UT on 25 October 2008, the Fermi GBM triggered and located
GRB 081025 (trigger 246615786 / 081025349) which was also detected by the
SWIFT-BAT Slew Survey (A. Copete et al. 2008, GCN 8409) and followed up by
SWIFT-XRT (J. Mao et al. 2008, GCN 8411). The GBM on-ground location is
consistent with the Swift position. 

The GBM light curve shows a multipeaked structure with a duration (T90) of
about 45 s (8-1000 keV). The time-averaged spectrum from T0-1.536 s to 
T0+24.064 s is best fit by an exponentially cutoff power law model with 
Epeak = 251 +/- 25 keV, and index -0.35 +/- 0.13 (chi squared 736 for 700 
d.o.f.). The event fluence (8-1000 keV) in this time interval is 
(7.1 +/- 0.5)E-06 erg/cm^2. The 1-sec photon flux measured from T+2.56 sec
in the 8-1000 keV band is 4.50 +/- 0.22  ph/cm2/sec. A Band function fit
the spectrum equally well (chi squared 732 for 699 d.o.f.) with 
Epeak= 200 +/- 33 keV, alpha = 0.15 +/- 0.22 and beta = -2.05 +/- 0.25. 

The spectral analysis results presented above are preliminary; final results

will be published in the GBM GRB Catalog."