[vsnet-grb-info 19174] GRB 170306B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20827
SUBJECT: GRB 170306B: Fermi GBM detection
DATE:    17/03/06 19:32:55 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

P. Veres (UAH), C. Meegan (UAH) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:

"At 14:07:22.27 UT on 6 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170306B (trigger 510502047 / 170306588),
which was also detected by Fermi/LAT (Omodei et al., GCN 20826). The
GBM on-ground location is consistent with the LAT position.


The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed
to the GBM in-flight location.

The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 18.7 s (50-300 keV).
The time-averaged spectrum from T0-3.8 s to T0+26.9 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.73 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 289 +/- 10 keV.


The event fluence (10-1000 keV) in this time interval is
(3.07 +/- 0.06)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.7 s in the 10-1000 keV band
is 12.4 +/- 0.3 ph/s/cm^2.

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