[vsnet-grb-info 20670] GRB 180611A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22768
SUBJECT: GRB 180611A: Fermi GBM observation
DATE:    18/06/12 19:40:00 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi at ba.infn.it>

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


"At 03:29:01.46 UT on 11 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180611A (trigger 550380546 / 180611145),
which was also reported by Hurley et al. 2018 (GCN 22767).
The GBM location is consistent with the IPN triangulated box.

The angle from the Fermi LAT boresight at the GBM trigger time is 62 degrees.

The GBM light curve shows a multipeaked emission episode
with a duration (T90) of about 9 s (50-300 keV).
The time-averaged spectrum from T0-1 s to T0+10 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.95 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 253 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(5.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 8.4 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 219 +/- 30 keV, alpha = -0.9 +/- 0.1 and
beta = -2.4 +/- 0.3.


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