[vsnet-grb-info 24019] GRB 191031D: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26118
SUBJECT: GRB 191031D: Fermi GBM detection
DATE:    19/11/01 03:22:35 GMT
FROM:    Bagrat Mailyan at UAH  <bm0054 at uah.edu>

B. Mailyan (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 21:23:31.13 UT on 31 October 2019, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 191031D (trigger 594249816/191031891)
which was also detected by the Swift BAT and XRT (D'Elia et al. 2019, GCN
26112)
The Fermi GBM Final Real-time Localization (GCN 26111) is consistent with
the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 64
degrees.

The GBM light curve shows a short spike with a duration (T90) of about
0.256 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.32 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.42 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 856 +/- 53 keV

The event fluence (10-1000 keV) in this time interval is
(4.36 +/- 0.09)E-06 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.128 s in the 10-1000 keV band
is 48.7 +/- 1.59 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"