GRB 230320B: Fermi GBM Observation

"At 21:12:25 UT on 20 March 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230320B (trigger 701039550/230320884). which was also detected by AstroSat (P K. Navaneeth et al. 2023, GCN 33492), Swift/BAT-GUANO (S. Ronchini et al. 2023, GCN 33499) CALET (T. Tamura et al. 2023, GCN 33501), and GRBAlpha (M. Dafcikova et al. 2023, GCN 33503). The on-ground calculated location, using the GBM trigger data, is RA = 28.11, DEC = 68.88 (J2000 degrees, equivalent to 01 h 52 m, 68 d 53' ), with a statistical uncertainty of 2.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). The angle from the Fermi LAT boresight is 140 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0+0.003 to T0+15.616 s is best fit by a power law function with an exponential high-energy cutoff.The power law index is -0.30 +/- 0.09 and the cutoff energy, parameterized as Epeak = 186 +/- 8 keV. The event fluence (10-1000 keV) in this time interval is (1.02 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0 s in the 10-1000 keV band is 12.7 +/- 0.6 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/"