[vsnet-grb-info 8044] GRB 090625B: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9583
SUBJECT: GRB 090625B: Fermi GBM observation
DATE:    09/06/26 21:49:03 GMT
FROM:    Arne Rau at MPE  <arau at mpe.mpg.de>

Arne Rau (MPE) reports on behalf of the Fermi GBM Team:

"At 13:26:22.51  UT on 25 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090625B (trigger 267629184 / 090625560)
which was also detected by the INTEGRAL (Goetz et al. 2009, GCN 9572).
The GBM on-ground location is consistent with the INTEGRAL position.
 
The angle from the Fermi LAT boresight is 125 degrees.

The GBM light curve consists of a single pulse
with a duration (T90) of about 13.6 s (8-1000 keV).
The time-averaged spectrum from T0-2.048 s to T0+6.144 s is
well fit  by a power law function with an exponential
high energy cutoff.  The power law index is -0.9 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 165 +/- 28 keV
(chi squared 429 for 453 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.04 +/- 0.13)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+3.072 s in the 8-1000 keV band
is 1.87 +/- 0.09 ph/s/cm^2.

A Band function fits the spectrum equally well (chi squared 424 for 454 
d.o.f.)
with Epeak= 100 +/- 32 keV, alpha = -0.4 +/- 0.5, and beta -2.0 +/- 0.2.

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