GCN Circular 32885

A. Ursi, F. Longo (Univ. Trieste and INFN Trieste), C. Pittori, F.
Verrecchia (SSDC, and INAF/OAR), 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), A. Bulgarelli, A. Di Piano, V. Fioretti,
G. Panebianco, N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli (SSDC, and
INAF/OAR), M. Romani (INAF/OA-Brera), M. Marisaldi (INAF/OAS-Bologna, and
Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma
(ASI), A. Giuliani (INAF/IASF-Mi), and P. Tempesta (TeleSpazio), report on
behalf of the AGILE Team:

The AGILE satellite detected the GRB 221028A at T0 = 2022-10-28 13:16:27 s
(UTC), reported by Swift BAT (GCN #32874
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 ). The burst is clearly visible in
the AGILE scientific ratemeters of the MiniCALorimeter (MCAL; 0.4-100 MeV)
and AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 2 s
and it released a total number of 3155 counts in the MCAL detector (above a
background rate of 1180 Hz), and 7270 counts in the AC detector (above a
background rate of 3410 Hz). The AGILE ratemeters light curves can be found
at http://www.agilescienceapp.it/notices/GRB221028A_AGILE_RM.png .

The event also triggered a high time resolution MCAL data acquisition, from
T0-4.31 s to T0+33.35 s (UTC), and released 1924 counts in the detector,
above a background rate of 477 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/GRB221028A_080686_594047787.000000.png
. The time-integrated spectrum of the burst between T0-2s and T0+7s be
fitted in the energy range 0.4-10 MeV with a power-law with ph. ind. =
-2.65 (-0.39/+0.50), resulting in a reduced chi-squared of 0.78 (48 d.o.f.)
and a fluence of 3.1e-06 ergs/cm^2 (90% confidence level), in the same
energy range. At the T0, the event was 49 deg off-axis.

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.