[vsnet-grb-info 21463] GRB 181225A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23562
SUBJECT: GRB 181225A: Fermi GBM detection
DATE:    18/12/26 03:56:19 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

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

"At 11:44:10.53 UT on 25 December 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181225A (trigger 567431055/ 181225489),
which was also detected by the Fermi LAT (M. Arimoto et al. 2018, GCN
23561).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 44 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 41.5 s (50-300 keV).
The time-averaged spectrum from T0-2.0 s to T0+36.8 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.04 +/- 0.10 and
the cutoff energy, parameterized as Epeak, is 1887 +/- 966 keV.

The event fluence (10-1000 keV) in this time interval is
(5.569 +/- 0.370)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.54 s in the 10-1000 keV band
is 3.74 +/- 0.19 ph/s/cm^2.

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