//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31726 SUBJECT: GRB 220308B: Fermi GBM detection DATE: 22/03/10 01:57:07 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA), O. J. Roberts (USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 05:35:30.10 UT on 08 March 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220308B (trigger 668410535 / 220308233). The on-ground calculated location, using the GBM trigger data, is RA = 292, DEC = 26 (J2000 degrees, equivalent to 19 h 27 m, 26 d 26'), with a statistical uncertainty of 5 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 at the GBM trigger time is 78 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 33 s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+32.769 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 342 +/- 93 keV, The event fluence (10-1000 keV) in this time interval is (4.4 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.512 s in the 10-1000 keV band is 1.9 +/- 0.2 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-001: CTIME (daily version) The counts accumulated every 0.256 seconds in 8 energy channels for each of the 14 detectors. GS-002 fermi.gsfc.nasa.gov