TITLE:   GCN CIRCULAR
NUMBER:  30106
SUBJECT: GRB 210531A: AGILE/MCAL detection (Fermi Trigger 644155206 / GRB 210531500)
DATE:    21/05/31 14:19:02 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi (INAF/IAPS), F. Longo (Univ. Trieste and INFN Trieste), 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,
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), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:

The AGILE satellite detected the long GRB 210531A at T0 = 2021-05-31
12:00:02.66 +/- 0.01 s (UTC), reported by Fermi/GBM (Trigger no. 644155206)
and BALROG (GCN #30105).

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 9650 counts in the SA detector (above a
background rate of 90 Hz), 53900 counts in the MCAL detector (above a
background rate of 1400 Hz), and 151900 counts in the AC detector (above a
background rate of 3780 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB210531A_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition.

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.