GCN Circular 40713

E. Neights (GWU, NASA GSFC) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 14:53:16.58 UT on 12 June 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250612C (trigger 771432801/250612620).
which was also detected by SVOM/GRM (Wang et al. 2025, GCN 40708
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 ).

The Fermi-GBM position was reported in GCN 40708
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  (Fermi GBM Team 2025).

The angle from the Fermi LAT boresight is 96 degrees.

The GBM light curve consists of multiple emission episodes with a duration (T90)
of about 1.62 s (50-300 keV). The time-averaged spectrum
from T0-0.128 to T0+2.688 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.97 +/- 0.01 and the cutoff energy,
parameterized as Epeak, is 2110 +/- 70 keV.

A Band function fits the spectrum equally well with Epeak = 2110 +/- 70 keV,
alpha = -0.97 +/- 0.01, and beta = -4 +/- 1.

The event fluence (10-1000 keV) in this time interval is
(2.80 +/- 0.02)E-05 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.77 s in the 10-1000 keV band is 154 +/- 3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"