TITLE: GCN CIRCULAR NUMBER: 38257 SUBJECT: GRB 241115C: Fermi GBM Observation DATE: 24/11/16 21:50:57 GMT FROM: Lorenzo Scotton at UAH L. Scotton (UAH), S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 04:35:33.96 UT on 15 November 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 241115C (trigger 753338138/241115191). which was also detected by Swift/BAT-GUANO (S. Ronchini et al. 2024, GCN 38245). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 257.26, Dec = 16.20 (J2000 degrees, equivalent to J2000 17h 9m, +16d 11'), with a statistical uncertainty of 4.91 degrees. The Fermi GBM on-ground location is consistent with the Swift/BAT-NITRATES position. The angle from the Fermi LAT boresight is 66 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 5.1 s (50-300 keV). The time-averaged spectrum from T0-1.0 to T0+7.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.77 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 53 +/- 7 keV. The event fluence (10-1000 keV) in this time interval is (2.1 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 9.9 +/- 0.4 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak = 51 +/- 7 keV, alpha = -1.72 +/- 0.11 and beta = -2.61 +/- 0.49. 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/"