GCN Circular 14094
David Yu and David Gruber (both MPE) report on behalf of the Fermi GBM Team: "At 07:30:01.58 UT on 17 December 2012, the Fermi Gamma-Ray Burst Monitor triggered and located a burst (trigger 377422204 / 121217313), whose location is consistent with the Swift GRB 121217A (Siegel et al. GCN 14089) which triggered BAT ~13 minutes prior to the GBM. Upon closer examination, we found that GRB 121217A is also present in the GBM data. GBM did not trigger on this earlier emission period owing to the triggering being disabled while Fermi was passing through a region of high geomagnetic latitude. The GBM light curve consists of two epochs of emission, separated by an epoch of quiescence of about 700 s. The duration of the first pulse is about 50 s while the second pulse is about 30 s long. The overall event T90 is about 780 s (50-300 keV). The time-averaged spectrum of the first emission epoch, from T0-749.6 s to T0-704.5 s, is well fit by a power law function with an exponential high-energy cutoff. The power law index is -1.20 +/- 0.12 and the cutoff energy, parameterized as Epeak, is 264 +/- 75 keV. The time-averaged spectrum of the second emission epoch, from T0-8.2 s to T0+24.6 s, is well fit by the same model, having a power law index of -1.29 +/- 0.14 and an Epeak of 184 +/- 56 keV. The event fluence (10-1000 keV) over the overall event is (1.11 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.68 s in the 10-1000 keV band is 3.47 +/- 0.29 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."