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GCN Circular 33780

GRB 230512A: Fermi-LAT detection
2023-05-12T18:34:10Z (a year ago)
N. Di Lalla at Stanford University <>
D. J. Maheso (Johannesburg Univ.), N. Di Lalla (Stanford Univ.), Khalil T. (Johannesburg Univ.), E. Bissaldi (Politecnico and INFN Bari), N. Omodei (Stanford Univ.), D. Kocevski (NASA/MSFC) and D. Horan (IN2P3/CNRS) report on behalf of the Fermi-LAT Collaboration:

At 06:27:45.41 on May 12, 2023, Fermi-LAT detected high-energy emission from GRB 230512A, which was also detected by Fermi-GBM (trigger 705565670/230512269, GCN 33778) and AstroSat (GCN 33779).

The best LAT on-ground location is found to be

RA, Dec = 295.4, 38.4 (degrees, J2000)

with an error radius of 0.3 deg (90% containment, statistical error only).
This was 45 deg from the LAT boresight at the time of the trigger.

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 100 MeV - 1 GeV photon flux in the time interval 0-300 s after the GBM trigger is (1.0 ± 0.3) E-05 ph/cm2/s. The estimated integrated photon index above 100 MeV is -2.15 ± 0.3.

The highest-energy photon is a 1.7 GeV event with 99% probability which is observed 84 seconds after the GBM trigger.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is Dimakatso Maheso ( <>)

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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