[vsnet-grb-info 24231] GRB 191202A: Fermi-LAT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26330
SUBJECT: GRB 191202A: Fermi-LAT detection
DATE:    19/12/03 20:04:05 GMT
FROM:    Lorenzo Scotton at CNRS/IN2P3/LUPM  <lorenzoscotton at live.it>

D. Kocevski (NASA/GSFC), R. Angioni (ASI/SSDC and INFN, Roma2), F. Longo (University and INFN, Trieste),

N. Omodei (Stanford University), E. Bissaldi (Politecnico and INFN, Bari) and L. Scotton (CNRS/IN2P3/LUPM, Montpellier)

report on behalf of the Fermi-LAT Collaboration:


On December 2nd, 2019, Fermi-LAT detected high-energy emission from

GRB 191202A, which was also detected by Fermi-GBM (trigger 597012536/191202867) (Veres et al. 2019, GCN 26329).


The best LAT on-ground location is found to be


RA, Dec = 249.54, 17.56 (degrees, J2000)


with an error radius of 0.24 deg (90% containment, statistical error only).

This was 11.4 deg from the LAT boresight at the time of the GBM trigger:


T0 = 20:48:51.23 UT.


The data from the Fermi-LAT show a significant increase
in the event rate after the GBM trigger that is spatially correlated with the
GBM emission with high significance.
The photon flux above 100 MeV in the time interval 0-1000s after the
GBM trigger is 2.6e-06 +/- 8.8e-07 ph/cm2/s.



The estimated photon index above 100 MeV is -1.6 +/- 0.2.




The highest-energy photon is a 1.8 GeV event which is observed 393 seconds

after the GBM trigger.


The Fermi-LAT point of contact for this burst is

Lorenzo Scotton (lorenzo.scotton at lupm.in2p3.fr).



The Fermi-LAT is a pair conversion telescope designed to cover

the energy band from 20 MeV to greater than 300 GeV.

It is the product of an international collaboration between

NASA and DOE in the U.S. and many scientific institutions

across France, Italy, Japan and Sweden.