TITLE: GCN CIRCULAR NUMBER: 40362 SUBJECT: GRB 250506A: Fermi GBM Observation DATE: 25/05/06 13:07:40 GMT FROM: Rushikesh Sonawane at IISER, TVM rushikesh23@iisertvm.ac.in
R. Sonawane (IISER, TVM), S. Bala (USRA), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 02:23:22.60 UT on 06 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250506A (trigger 768191007/250506100). which was also detected by SVOM/ECLAIRs (Wang et al. 2025, GCN 40358). The Fermi GBM on-ground location is consistent with the SVOM/ECLAIRs position.
The angle from the Fermi LAT boresight is 116 degrees.
The GBM light curve consists of multiple emission episodes with a duration (T90) of about 48 s (50-300 keV). The time-averaged spectrum from T0+0.003 to T0+61.441 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 280 +/- 20 keV.
The event fluence (10-1000 keV) in this time interval is (2.36 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+34 s in the 10-1000 keV band is 27.4 +/- 0.5 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/"
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