TITLE: GCN CIRCULAR NUMBER: 22875 SUBJECT: GRB 180630A: Fermi GBM detection DATE: 18/06/30 16:54:15 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH), A. von Kienlin (MPE), and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 11:11:54.41 UT on 30 June 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180630A (trigger 552049919 / 180630467) which was also detected by the Swift BAT and XRT instruments (D'Avanzo et al. 2018, GCN 22872). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 20 degrees. The GBM light curve consists of a single structured peak with a duration (T90) of about 12 s (50-300 keV). The time-averaged spectrum from T0-1.54s to T0+8.70 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.37 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 84 +/- 8 keV. A Band function fits the spectrum equally well with Epeak = 60 +/- 10 keV, alpha = -1.11 +/- 0.20, and beta = -2.32 +/- 0.16. The event fluence (10-1000 keV) in this time interval is (2.5 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.15 s in the 10-1000 keV band is 9.4 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."