[vsnet-grb-info 20799] GRB 180703B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22897
SUBJECT: GRB 180703B: Fermi GBM detection
DATE:    18/07/04 17:00:32 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S.Poolakkil and C. Meegan (both UAH) report on
behalf of the Fermi GBM Team:

"At 22:46:51.32 UT on 03 July 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180703B (trigger 552350816/ 180703949),
which was also detected by the Fermi LAT (Racusin et al. 2018, GCN 22884).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 31 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 1.6 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+2.4 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.79 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 138 +/- 3 keV.

The event fluence (10-1000 keV) in this time interval is
(8.281 +/- 0.119)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+1.21 s in the 10-1000 keV band
is 103.9 +/- 2.92 ph/s/cm^2.

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