[vsnet-grb-info 8458] GRB 090927: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9974
SUBJECT: GRB 090927: Fermi GBM observation
DATE:    09/09/30 13:01:46 GMT
FROM:    David Gruber at MPE  <dgruber at mpe.mpg.de>

D. Gruber (MPE), E. Bissaldi (MPE) and S. McBreen (UCD/MPE)
report on behalf of the Fermi GBM Team:


"At 10:07:17.21 UT on 27 September 2009, the Fermi Gamma-Ray Burst  
Monitor
triggered and located GRB 090927 (trigger 275738839 / 090927422),
which was also detected by the Swift-BAT (Grupe al. 2009, GCN 9945).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 85 degrees.

The GBM light curve consists of one weak pulse with
a duration of about 2 seconds.
The time-averaged spectrum from T0-0.256 s to T0+0.896 s is
adequately fit by a simple power law function
with index -1.47 +/- 0.06 (C-stat 330 for 239 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(6.1 +/- 0.5)E-07 erg/cm^2. The 128-msec peak photon flux measured
starting from T0-0.128 s in the 8-1000 keV band
is 7.2 +/- 0.9 ph/s/cm^2.


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