[vsnet-grb-info 21480] GRB 181228A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23579
SUBJECT: GRB 181228A: Fermi GBM observation
DATE:    18/12/28 14:35:02 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi at ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari) and P. Veres (UAH)
report on behalf of the Fermi GBM Team:


"At 02:53:14.96 UT on 28 December 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181228A (trigger 567658399 / 181228120),
which was also detected by the Swift/BAT (Moss et al. 2018, GCN 23570).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 72 degrees.

The GBM light curve consists of a two-peaked emission episode
with a duration (T90) of about 18 s (50-300 keV).
The time-averaged spectrum from T0 to T0+19 s is
best fit by a Band function with Epeak = 182 +/- 8 keV,
alpha = -0.82 +/- 0.03, and beta = -2.25 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(2.56 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+15.6 s in the 10-1000 keV band
is 16.0 +/- 0.4 ph/s/cm^2.


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