[vsnet-grb-info 20232] GRB 180113A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22328
SUBJECT: GRB 180113A: Fermi GBM observation
DATE:    18/01/13 17:45:19 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

P. Veres (UAH) reports on behalf of the Fermi GBM Team:

"At 02:47:06.14 UT on 13 January 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180113A (trigger 537504431 / 180113116).
which was also detected by the Swift/BAT (Ukwatta et al., GCN 22325).
The GBM on-ground location is consistent with the Swift position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the best location is 51 degrees.

The GBM light curve shows overlapping peaks
with a duration (T90) of about 11 s (50-300 keV).
The time-averaged spectrum from T0-1.4 s to T0+15.0 s is
best fit by a Band function with Epeak = 247 +/- 12 keV,
alpha = -0.59 +/- 0.04, and beta = -2.32 +/- 0.10.

The event fluence (10-1000 keV) in this time interval is
(1.007 +/- 0.012)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.45 s in the 10-1000 keV band
is 9.3 +/- 0.3 ph/s/cm^2.

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