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GCN Circular 32131

GRB 220527A: Fermi-LAT detection
2022-05-27T16:25:14Z (2 years ago)
Magnus Axelsson at Stockholm U. <>
E. Bissaldi (Politecnico and INFN Bari), L. Scotton (CNRS/IN2P3/LUPM) and M. Axelsson (KTH & Stockholm Univ.) report on behalf of the Fermi-LAT team:

On May 27, 2022, Fermi-LAT detected high-energy emission from GRB 220527A, which was also detected by

Fermi-GBM (trigger 675335840 / 220527387, GCN 32130) and AGILE (Ursi et al. 2022. GCN 32129).

The best LAT on-ground location is found to be

RA, Dec = 323.57, -14.9  (degrees, J2000)

with an error radius of 0.08 deg (90 % containment, statistical error only). This was 49 deg from the LAT boresight at the time of the GBM trigger:

T0 = 09:17:15.73 UT.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-1000 s after the GBM trigger is (6.0 +/- 1.4)E-06 ph/cm2/s. The estimated photon index above 100 MeV is -2.0 +/- 0.2. The highest-energy photon is a 12 GeV event which is observed 89 seconds after the GBM trigger.

The Fermi-LAT point of contact for this burst is Elisabetta Bissaldi (<>).

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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