[vsnet-grb-info 12164] GRB 120728B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13553
SUBJECT: GRB 120728B: Fermi GBM detection
DATE:    12/07/31 20:59:26 GMT
FROM:    Suzanne Foley at MPE  <sfoley at mpe.mpg.de>

S. Foley (UCD/MPE)
reports on behalf of the Fermi GBM Team:

"At 10:25:24.24 UT on 28 July 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120728B (trigger 365163927 / 120728434)
which was also detected by Konus-Wind
(Golenetskii et al., GCN 13552).
This burst was localized by the IPN (Hurley et al., GCN 13549).
The GBM on-ground calculated location is consistent with the
IPN location.

The angle from the Fermi LAT boresight is 117 degrees.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous repoint request (ARR) maneuver.

The GBM light curve consists of multiple pulses
with a duration (T90) of about 105 s (50-300 keV).
The time-averaged spectrum from T0+8.7 s to T0+113.2 s is
well fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.31 +/-0.01 and
the cutoff energy, parameterized as Epeak, is
94.86 (+1.04/-1.01) keV.

The event fluence (10-1000 keV) in this time interval is
(1.27 +/- 0.02)E-4 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+69.6 s in the 10-1000 keV band
is 42.8 +/- 0.6 ph/s/cm^2.


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