[vsnet-grb-info 21253] GRB 181020A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23352
SUBJECT: GRB 181020A: Fermi GBM detection
DATE:    18/10/21 04:22:04 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

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

"At 19:00:33.30 UT on 20 October 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181020A (trigger 561754838 / 181020792).
which was also detected by Fermi/LAT (Axelsson GCN 23350) and Swift/BAT
(Moss et al., GCN 23349). The GBM on-ground location is consistent with the
Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 50
degrees.


The GBM light curve shows a single bright pulse
with a duration (T90) of about 15 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+20.5 s is
best fit by a Band function with Epeak = 367 +/- 17 keV,
alpha = -0.70 +/- 0.02, and beta = -2.06 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(3.07 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.4 s in the 10-1000 keV band
is 16.6 +/- 0.3 ph/s/cm^2.

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