TITLE: GCN CIRCULAR NUMBER: 37660 SUBJECT: GRB 240930B: Fermi GBM Observation DATE: 24/10/01 19:59:50 GMT FROM: Jacob Smith at Fermi-GBM Team jrs0118@uah.edu
J. Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
At 17:18:02 UT on 30 Sep 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240930B (trigger 749409487 / 240930721), and was detected by Einstein Probe Wide-field X-ray Telescope (EP-WXT) (X. Tian et al. 2024, GCN 37648), Einstein Probe Follow-up X-ray Telescope (EP-FXT) (H. L. Peng et al. 2024, GCN 37653), and Swift-BAT (J. DeLaunay et al. 2024, GCN 37654). The Fermi GBM on-ground location is consistent with the EP-WXT, EP-FXT, and Swift-BAT localizations.
The angle from the Fermi LAT boresight is 113 degrees.
The GBM light curve single emission episode with a duration (T90) of about 64.3 s (50-300 keV). The time-averaged spectrum from T0-9.7 to T0+74.2 s is best fit by a Band function with Epeak = 86 +/- 10 keV, alpha = -0.70 +/- 0.14, and beta = -2.03 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is (1.7 +/- 0.06)E-05 erg/cm^2. The 1.024-s peak photon flux measured starting from T0+3.3 s in the 10-1000 keV band is 9.2 +/- 0.4 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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