TITLE:   GCN CIRCULAR
NUMBER:  36716
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 240619C
DATE:    24/06/20 21:16:24 GMT
FROM:    sumanbala2210@gmail.com

S. Bala (USRA) reports on behalf of the Fermi-GBM Team:

AstroSat CZTI detected GRB 240619C at 2024-06-19 23:44:51.50 UTC (GCN 36711).
There was a Fermi-GBM onboard accidental trigger around 420s before GRB 240619C.
Due to the Fermi-GBM trigger latency, we were unable to trigger immediately on the GRB.

The GRB 240619C can be partially seen in the trigger data (trigger 740533060 / 240619984).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 340.68, Dec = -71.85 (J2000 degrees, equivalent to
J2000 22h 43m, -71d 51'), with a statistical uncertainty of 1.15 degrees.

The angle from the Fermi LAT boresight is 56 degrees.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals, was used to identify GRB-like emission episodes at around the AstroSAT GCN time. We find multiple emission peaks, each with a localization consistent with the on-ground localization from the Trigdat data. The brightest peak (at Fermi MET 740533496.5 s) was
found to be the most significant (S/N of 15) on the 2.048 s timescale, with a false alarm rate of 5.4e-06 Hz, using the standard search protocol. The GBM targeted search found this
brightest peak to have a "hard" GRB spectrum (Cut-off Power Law function with Epeak=1500 keV, alpha = -1.5 )


[1] Goldstein et al. 2019 arXiv:1903.12597