[vsnet-grb-info 19249] GRB 170325A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20940
SUBJECT: GRB 170325A: Fermi GBM observation
DATE:    17/03/27 17:35:41 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi at uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), M. Stanbro,
and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 07:56:58.04 UT on 25 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170325A (trigger 512121423/170325331),
which was also detected by the Swift/BAT (Palmer et al. 2017, GCN 20938).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 0.58 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.7 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 600 +/- 200 keV.

The event fluence (10-1000 keV) in this time interval is
(4.8 +/- 0.6)E-7 erg/cm^2. The 64-ms peak photon flux, measured
starting from T0 in the 10-1000 keV band, is 7.6 +/- 1.1 ph/s/cm^2.


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