GCN Circular 33655
C. Malacaria (ISSI) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 07:32:35.96 UT on 02 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230402A (trigger 702113560 / 230402314, GCN 33553), which was also detected by AGILE (GCN 33555), AstroSat CZTI (GCN 33562), CALET (GCN 33563) and Fermi-LAT (GCN 33650). The Fermi GBM Final Real-time Localization (GCN 33553) is consistent with the Fermi-LAT position. The angle from the Fermi LAT boresight is 24 degrees. The GBM light curve consists of a main peak with a duration (T90) of about 63 s (50-300 keV). The time-averaged spectrum from T0 s to T0+46 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.94 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 1030 +/- 81 keV. A Band function fits the spectrum equally well with Epeak= 995 +/- 85 keV, alpha = -0.93 +/- 0.02 and beta = -2.9 +/- 0.5 . The event fluence (10-1000 keV) in this time interval is (3.99 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.3 s in the 10-1000 keV band is 10.7 +/- 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/"