[vsnet-grb-info 20558] GRB 180418A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22656
SUBJECT: GRB 180418A: Fermi GBM observation
DATE:    18/04/18 20:00:05 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

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


"At 06:44:06.28 UT on 18 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180418A (trigger 545726651 / 180418281),
which was also detected by the Swift/BAT (D'Elia et al. 2018, GCN 22646).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 78 degrees.

The GBM light curve consists of a signle FRED-like peak,
with a duration (T90) of about 2.5 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.77 s is
adequately fit by a simple power law function with index -1.52 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(7.6 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.26 s in the 10-1000 keV band
is 7.56 +/- 1.13 ph/s/cm^2.


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