GCN Circular 31309

A. Ursi (INAF/IAPS), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), F.
Longo (Univ. Trieste and INFN Trieste), M. Tavani (INAF/IAPS, and Univ.
Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, L.
Foffano, E. Menegoni, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and
INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani
(INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University),
M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), A. Giuliani
(INAF/IASF-Mi), report on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a long burst at T0 = 2021-12-26
05:25:41.00 +/- 0.01 s (UTC) (INTEGRAL SPI-ACS trigger Tri,Sub: 9576,0).

The event lasted about 20 s and released a total number of 2736 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 613 Hz. The MCAL light curve shows several peaks and can be found
at http://www.agilescienceapp.it/notices/GRB211226A_AGILE_MCAL.png .

The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event released a total
number of 492 counts in the SA detector (above a background rate of 115
Hz), 5996 counts in the MCAL detector (above a background rate of 1290 Hz),
and 16770 counts in the AC detector (above a background rate of 3530 Hz).
The AGILE ratemeter light curves can be found at
http://www.agilescienceapp.it/notices/GRB211226A_AGILE_RM.png .

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.
Automatic MCAL GRB alert Notices can be found at:
https://gcn.gsfc.nasa.gov/agile_mcal.html.