GCN Circular 23524

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."