TITLE: GCN CIRCULAR NUMBER: 30557 SUBJECT: GRB 210730A: Fermi GBM observation DATE: 21/07/30 21:05:04 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi GBM Team: "At 04:57:29.03 UT on 30 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210730A (trigger 649313854 / 210730207) which was also detected by the Swift/BAT and Swift/XRT (E. Sonbas et al. 2021, GCN 30548). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 32 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 5 s (50-300 keV). The time-averaged spectrum from T0 to T0+6 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.68 +/- 0.07 and the cutoff energy, parameterized as Epeak, is 170 +/- 11 keV The event fluence (10-1000 keV) in this time interval is (2.9 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.3 s in the 10-1000 keV band is 10.5 +/- 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/"