TITLE:   GCN CIRCULAR
NUMBER:  26119
SUBJECT: GRB 191031C: Fermi GBM detection
DATE:    19/11/01 03:48:32 GMT
FROM:    Cori Fletcher at USRA  <cfletcher@usra.edu>

C. Fletcher (USRA), R. Hamburg (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 18:43:16.71 UT on 31 October 2019, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 191031C (trigger 594240201 / 191031780)
which was also detected by the Swift BAT and XRT (Ambrosi et al. 2019, GCN 26108).
The Fermi GBM Final Real-time Localization (GCN 26107) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 20 degrees.

The GBM light curve shows a complex, multi-peaked structure
with a duration (T90) of about 78 s (50-300 keV).
The time-averaged spectrum from T0+3.3  s to T0+81.2 s is
best fit by a Band function with Epeak = 107 +/- 9 keV,
alpha = -0.5 +/- 0.1, and beta = -2.3 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(1.33 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+42.2 s in the 10-1000 keV band
is 7.3 +/- 0.3 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/"