GCN Circular 36462

S. Cutini (INFN Perugia), E. Bissaldi (Politecnico and INFN Bari), R. Gupta (NASA/GSFC) and N. Di Lalla (Stanford University) report on behalf of the Fermi-LAT Collaboration:

On May 13, 2024 Fermi-LAT detected high-energy emission from GRB 240513A, which was also detected by Fermi-GBM (trigger 737277727 / 240513307) and AstroSat CZTI (GCN #36455).

The best LAT on-ground location is found to be

RA, Dec = 163.4, -27.5 (J2000)

with an error radius of 0.4 deg (90 % containment, statistical error only). This was 34 deg from the LAT boresight at the time of the GBM trigger:

T0 = 07:22:02.55 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 0-100 s after the GBM trigger is (1.7 +/- 0.6) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.3 +/- 0.4. The highest-energy photon is a 0.8 GeV event which is observed about 5 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Sara Cutini (sara.cutini@pg.infn.it).

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.