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GCN Circular 27151

Subject
GRB 200219C: Fermi-LAT detection
Date
2020-02-20T07:49:00Z (4 years ago)
From
Makoto Arimoto at Tokyo Inst of Tech <arimoto@hp.phys.titech.ac.jp>
F. Dirirsa (Univ. of Johannesburg), M. Arimoto (Kanazawa Univ.), M.
Axelsson (KTH & Stockholm Univ.), F. Longo (University & INFN
Trieste), and N. Omodei (Stanford U.)
report on behalf of the Fermi-LAT Collaboration:

On February 19, 2020, Fermi-LAT detected high-energy emission from
GRB 200219C, which was also detected by Fermi-GBM (trigger
603849435/200219998, GCN 27145).

The best LAT on-ground location is found to be

RA, Dec = 262.7, 10.5 (degrees, J2000)

with an error radius of 0.24 deg (90% containment, statistical error only).
This was 43 deg from the LAT boresight at the time of the GBM trigger:

T0 = 23:57:10.3 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 (2.7 degrees from the GBM position) with high significance.
The photon flux above 100 MeV in the time interval 0-1500 s after the
GBM trigger is 2.2 +/- 0.8 e-6 ph/cm2/s.

The estimated photon index above 100 MeV is -2.1 +/- 0.3.

The highest-energy photon is a 1.17 GeV event which is observed 344.6 seconds
after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is
Feraol Fana Dirirsa (fdirirsa@uj.ac.za).

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.
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