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GCN Circular 30969

Subject
GRB 211023A: AGILE detection
Date
2021-10-24T09:42:45Z (2 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
A. Ursi, M. Cardillo (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), A. Argan, C. Casentini, Y. Evangelista, E. Menegoni, L. Foffano,
G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and
INAF/OAR), A. Bulgarelli, A. Di Piano, 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), F.
Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:

The AGILE satellite detected the long GRB 211023A at T0 = 2021-10-23
13:07:58 s (UTC), reported by Fermi GBM (GCNs #30958, #30965) and Fermi LAT
(GCN #30961).

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 lasted about 45 s and
it released a total number of 5300 counts in the SA detector (above a
background rate of 90 Hz), 64325 counts in the MCAL detector (above a
background rate of 1200 Hz), and 233020 counts in the AC detector (above a
background rate of 2810 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB211023A_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition, from T1 = 2021-10-23 13:07:32.91 s +/- 0.01 (UTC) to T2 =
2021-10-23 13:08:05.20 +/- 0.01 s (UTC), and released 12480 counts in the
detector, above a background rate of 620 Hz. The time-integrated spectrum
of the first 17 s of the burst can be fitted in the energy range 0.4-50 MeV
with a single power-law with ph. ind. = -2.45 (-0.27/+0.34), resulting in a
reduced chi-squared of 0.89 (75 d.o.f.) and a fluence of 1.3e-05 ergs/cm^2
(90% confidence level), in the same energy range. The MCAL light curve can
be found at:
http://www.agilescienceapp.it/notices/075364_GRB211023A_562079268.000000.png
.

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.
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