[vsnet-grb-info 8032] GRB 090625: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9571
SUBJECT: GRB 090625: Fermi GBM detection
DATE:    09/06/25 14:15:33 GMT
FROM:    Arne Rau at MPE  <arau at mpe.mpg.de>

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

"At 05:37:00.21 UT on 25 June 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090625 (trigger 267601022  / 090625234).

The on-ground calculated location, using the GBM trigger
data, is RA = 20.3, DEC = -6.4 (J2000 degrees,
equivalent to 01 h 21 m, -06 d 24'), with an uncertainty
of 3.1 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 13 degrees.

The GBM light curve shows multiple weak pulses
with a duration (T90) of about 51 s (8-1000 keV).
The time-averaged spectrum from T0-6.144 s to T0+12.288 s is
well fit by a power law function with an exponential
high energy cutoff.  The power law index is -0.6 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 198 +/- 36 keV
(chi squared 551 for 579 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(8.8 +/- 1.2)E-07 erg/cm^2. The 4.096-sec peak photon flux measured
starting from T0+4.096 s in the 8-1000 keV band
is 0.50 +/- 0.02 ph/s/cm^2.

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