[vsnet-grb-info 20538] GRB 180411A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22634
SUBJECT: GRB 180411A: Fermi GBM detection
DATE:    18/04/12 02:41:57 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S. Poolakkil (UAH), A. von Kienlin (MPE) and C. Meegan (UAH) report on
behalf of the Fermi GBM Team:

"At 12:27:40.97 UT on 11 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180411A (trigger 545142465 / 180411519),
which was also detected by the Swift/BAT (Liu et al. 2018, GCN 22630).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 150 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 77.6 s (50-300 keV).
The time-averaged spectrum from T0-3.1 s to T0+79.8 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.18 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 358 +/- 30 keV.

The event fluence (10-1000 keV) in this time interval is
(3.276 +/- 0.085)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+54.27 s in the 10-1000 keV band
is 10.5 +/- 0.79 ph/s/cm^2.

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