[vsnet-grb-info 6837] GRB 081021: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8432
SUBJECT: GRB 081021: Fermi GBM detection
DATE:    08/10/28 16:27:20 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 09:33:28 UT on 21 October 2008, the Fermi GBM triggered
and located GRB 081021 (trigger 246274409 / 081021398).
The on-ground calculated location, using the GBM trigger
data, is RA = 197.9, DEC = -25.1 (J2000 degrees,
equivalent to 13h 12m, +25d 06'), with an uncertainty
of 2.2 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 Fermi LAT boresight is 125 degrees.

This GRB has one isolated peak, which is about 25 sec long. 
The time-averaged spectrum (10-1000 keV) from T0-3.8 s to T0+15.6 s 
is best fit by a Band function with Epeak = 117 +/- 11 keV, 
alpha = 0.11 +/- 0.25, and beta = -2.8 +/- 0.4.

The fluence (10-1000 keV) in this time interval from the
Band model is (5.3 +/- 0.6)E-06 erg/cm^2. 
The 1 sec peak photon flux measured starting from T0+2.3 s 
in the 10-1000 keV band is 4.2 +/- 0.9 ph/s/cm^2.

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