[vsnet-grb-info 20282] GRB 180204A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22378
SUBJECT: GRB 180204A: Fermi GBM detection
DATE:    18/02/04 14:24:46 GMT
FROM:    Adam Goldstein at Fermi-GBM/UAH  <adam.m.goldstein at msfc.nasa.gov>

P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 02:36:16.93 UT on 04 February 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180204A (trigger 539404581 / 180204109) which was also detected by the Swift/BAT (Page et al., GCN 22375).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 68 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 1.2 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+1.2 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.92 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 781 +/- 161 keV.

The event fluence (10-1000 keV) in this time interval is
(8.48 +/- 0.32)E-7 erg/cm^2. The 64-msec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 19.7 +/- 1.6 ph/s/cm^2.

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