[vsnet-grb-info 19959] GRB 171022A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22046
SUBJECT: GRB 171022A: Fermi GBM detection
DATE:    17/10/23 22:38:55 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007 at uah.edu>

R. Hamburg (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 21:14:20.77 UT on 22 October 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171022A (trigger 530399665 / 171022885).
which was also detected by the Fermi/LAT
(Palatiello et al. 2017, GCN 22045).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 99
degrees.

The GBM light curve shows a multi-peaked structure
with a duration (T90) of about 13 s (50-300 keV).
The time-averaged spectrum from T0-0.00 s to T0+15.07 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.49 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 151 +/- 5 keV.

The event fluence (10-1000 keV) in this time interval is
(8.1 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.23 s in the 10-1000 keV band
is 8.7 +/- 0.3 ph/s/cm^2.

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