TITLE: GCN CIRCULAR NUMBER: 33151 SUBJECT: GRB 230102A: Fermi GBM Observation DATE: 23/01/05 18:21:17 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:22:13 UT on 02 January 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230102A (trigger 694311737/230102015). which was also detected by Swift/BAT-GUANO (J. DeLaunay et al. 2023, GCN 33147), GRBAlpha (M. Dafcikova et al 2023, GCN 33143) and AGILE (A. Ursi et al. 2023, GCN 33138). The Fermi GBM Localization was reported in GCN 33137. The angle from the Fermi LAT boresight is 65 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 0.18 s (50-300 keV). The time-averaged spectrum from T0-0.06 to T0+0.19 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.94 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 1508 +/- 260 keV. The event fluence (10-1000 keV) in this time interval is (1.43 +/- 0.05)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0 s in the 10-1000 keV band is 36 +/- 1 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/" FSSC: Data » Data Access » GBM - Fermi Gamma-ray Space Telescope ID Name Description; GS-106: GBM Burst Catalog Entry: Parameters describing the burst (e.g., durations, fluences). This file is used to create GBM Burst Catalog.: GS-109 fermi.gsfc.nasa.gov