TITLE: GCN CIRCULAR NUMBER: 23524 SUBJECT: GRB 181212A: Fermi GBM Detection DATE: 18/12/13 02:19:16 GMT FROM: C. Michelle Hui at MSFC/Fermi-GBM C. L. Fletcher (USRA) report on behalf of the Fermi GBM Team: "At 16:37:46.05 UT on 12 December 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181212A (trigger 566325471 / 181212693). The on-ground calculated location, using the GBM trigger data, is RA = 298.4, DEC = -3.7 (J2000 degrees, equivalent to 19 h 53 m 33.60 s, -03 d 42 '), with an uncertainty of 2.3 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 114 degrees. The GBM light curve consists of a bright pulse with a duration (T90) of about 58 s (50-300 keV). The time-averaged spectrum from T0+0 s to T0+58 s is best fit by a Band function with Epeak = 72 +/- 8 keV, alpha = -1.4 +/- 0.1, and beta = -2.2 +/- 0.1 The event fluence (10-1000 keV) in this time interval is (2.138 +/- 0.052)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.9 s in the 10-1000 keV band is 66 +/- 1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."