TITLE: GCN CIRCULAR NUMBER: 36685 SUBJECT: GRB 240615A: Fermi GBM Observation DATE: 24/06/17 14:47:05 GMT FROM: Oliver J Roberts at USRA/NASA oliver.roberts@nasa.gov
O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 17:51:45.05 UT on 15 June 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240615A (trigger 740166710/240615744), which was also detected by Swift BAT GUANO (DeLaunay et al. 2024, GCN 36672), KONUS-WIND (Frederiks et al. 2024, GCN 36677) and GECAM (Tan et al. 2024, GCN 36682). The Fermi-GBM Final Real-time location (Fermi GBM Team 2024, GCN 36671) is consistent with the Swift BAT-GUANO position.
The angle from the Fermi LAT boresight is 23 degrees.
The GBM light curve consists of bright, overlapping emission episodes with a duration (T90) of about 0.10 s (50-300 keV). The time-averaged spectrum from T0-0.03 to T0+0.09 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.52 +/- 0.07 and the cutoff energy, parameterized as Epeak, is 933 +/- 105 keV.
A Band function fits the spectrum equally well with Epeak= 858 +/- 110 keV, alpha = -0.48 +/- 0.08 and beta = -3.04 +/- 0.76.
The event fluence (10-1000 keV) in this time interval is (1.56 +/- 0.06)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 45 +/- 2 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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