TITLE: GCN CIRCULAR NUMBER: 33162 SUBJECT: GRB 230111A: Fermi GBM Observation DATE: 23/01/12 17:54:28 GMT FROM: Oliver J Roberts at USRA/NASA O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 19:07:42.90 UT on 11 January 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230111A (trigger 695156867/230111797), which was also detected by MAXI (K. Setoguchi et al. 2023, GCN 33157). The Fermi GBM Localization reported in GCN 33156 is consistent with the MAXI location. The angle from the Fermi LAT boresight is 108 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 9 s (50-300 keV). The time-averaged spectrum from T0-3.6 to T0+4.8 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.31 +/- 0.30 and the cutoff energy, parameterized as Epeak, is 122 +/- 16 keV. The event fluence (10-1000 keV) in this time interval is (1.16 +/- 0.12)E-06 erg/cm^2. The measured 1-s peak photon flux starting from T0-0.9 s in the 10-1000 keV band is 2.6 +/- 0.3 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/"