TITLE: GCN CIRCULAR NUMBER: 22288 SUBJECT: GRB 171227A: AGILE/MCAL detection DATE: 17/12/27 18:34:44 GMT FROM: Francesco Verrecchia at ASDC F. Verrecchia (SSDC and INAF/OAR), A.Ursi (INAF/IAPS), A. Trois (INAF/OA-Cagliari), C. Pittori (SSDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Marisaldi (INAF/IASF-Bo and Bergen University), N. Parmiggiani (INAF/IASF-Bo), F. Longo (Univ. Trieste and INFN Trieste), A. Bulgarelli (INAF/IASF-Bo), M. Cardillo, M. Pilia (INAF/OA-Cagliari), G. Piano (INAF/IAPS), I. Donnarumma (ASI), G. Minervini, A. Argan, Y. Evangelista (INAF/IAPS), F. Lucarelli (SSDC and INAF/OAR), V. Fioretti, F. Fuschino (INAF/IASF-Bo), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: The AGILE Mini-CALorimeter (MCAL) detected a long burst at T0 = 2017-12-27 00:00:30.00 +/- 0.01 UTC in the acquired data interval (following an internal trigger) started at T1=00:00:29.00 UTC and ended at 00:00:46.50 UTC. The MCAL light curve shows a multi-peaked structure, with the main part within T0+0.70 s and T0+5.50 s and a second short peak at T0+10.50 s. The main GRB interval released a total number of ~28190 counts at E>400 keV in the detector, above an average background rate of 23 counts/32ms. The AGILE-MCAL detector has a full solid angle acceptance, and is operational in the range 0.4 - 100 MeV.