[vsnet-grb-info 28551] GRB 210818A: AGILE detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30654
SUBJECT: GRB 210818A: AGILE detection
DATE:    21/08/18 08:27:40 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi at gmail.com>

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), C. Casentini
(INAF/IAPS), P. Tempesta (TeleSpazio), M. Tavani (INAF/IAPS, and Univ. Roma
Tor Vergata), A. Argan, M. Cardillo, Y. Evangelista, G. Piano (INAF/IAPS),
F. Lucarelli, C. Pittori,  (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), 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 210818A at T0 = 2021-08-18
01:02:08.19 s (UTC), reported by Swift (GCNs #30652, #30653).

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 35 s and
it released a total number of 3020 counts in the SA detector (above a
background rate of 70 Hz), 48170 counts in the MCAL detector (above a
background rate of 1250 Hz), and 130730 counts in the AC detector (above a
background rate of 3650 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB210818A_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition, from T1 = 2021-08-18 01:02:07.81 s +/- 0.01 (UTC) to T2
=2021-08-18 01:02:21.18 +/- 0.01 s (UTC), and released 21640 counts in the
detector, above a background rate of 625 Hz. The MCAL light curve can be
found at:
http://www.agilescienceapp.it/notices/074408_GRB_556333328.188243.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.