[vsnet-grb-info 19576] GRB 170710B: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21319
SUBJECT: GRB 170710B: Fermi GBM observation
DATE:    17/07/11 15:33:25 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007 at uah.edu>

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

"At 08:10:08.00 UT on 10 July 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170710B (trigger 521367012 / 170710340)
which was also detected by the Swift/BAT
(D. Palmer et al. 2017, GCN  21316)
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 49
degrees.

The GBM light curve consists of one main peak
with a duration (T90) of about 42 s (50-300 keV).
The time-averaged spectrum from T0-4 s to T0+28 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 293 +/- 61 keV.
A Band function fits the spectrum equally well
with Epeak= 149 +/- 49 keV, alpha = -0.9 +/- 0.2 and beta = -1.9 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(6.0 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.5 s in the 10-1000 keV band
is 2.7 +/- 0.3 ph/s/cm^2.

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