[vsnet-grb-info 26364] GRB 200920B: AGILE/MCAL detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28464
SUBJECT: GRB 200920B: AGILE/MCAL detection of a burst
DATE:    20/09/21 08:35:02 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi at gmail.com>

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C.
Casentini, 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 Mini-CALorimeter (MCAL) detected the short GRB 200920B at T0 =
2020-09-20 19:56:59.52 +/- 0.01 s (UTC), detected also by Fermi/GBM
(trigger 622324624 / 200920651).

The event lasted about 0.42 s and released a total number of ~505 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 540 Hz.

The time-integrated spectrum of the burst can be fitted in the energy range
0.4-5 MeV with a single power-law with ph.ind. = 2.41 -0.30/+0.37,
resulting in a reduced chi-squared of 1.14 (36 d.o.f.) and a fluence of
3.46e-7 ergs/cm^2 (90% confidence level), in the same energy range.

The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/GRB200920B_069656_527716619.529166.png
.

The event is also clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 18-60 keV), MCAL (0.4-100 MeV), and AntiCoincidence (50-200
keV) detectors. Their light curves can be found at:
http://www.agilescienceapp.it/notices/GRB200920B_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 Notice