[vsnet-grb-info 28269] GRB 210704A: AGILE/MCAL detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30372
SUBJECT: GRB 210704A: AGILE/MCAL detection
DATE:    21/07/05 09:00:27 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi at gmail.com>

A. Ursi (INAF/IAPS), 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, G. Piano (INAF/IAPS), F. Lucarelli (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 210704A at T0 =
2021-07-04 19:33:25.27 +/- 0.01 s (UTC) (Fermi trigger no.647120009).

The event lasted about 1.06 s and released a total number of ~1333 counts
in the detector (in the 0.4-100 MeV energy range), above an average
background rate of 574 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/073773_GRB_552512005.278593.png . The
time-integrated spectrum of the burst can be fitted in the energy range
0.4-10 MeV with a single power-law with ph.ind. = -2.54 -0.28/+0.34,
resulting in a reduced chi-squared of 0.77 (48 d.o.f.) and a fluence of
2.9e-06 ergs/cm^2 (90% confidence level), in the same energy range.

The event is also clearly visible in the scientific ratemeters of the
SuperAGILE (SA; 18-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The burst released 450 counts
in the SA detector (above a background rate of 60 Hz), 5040 counts in the
MCAL detector (above a background rate of 1100 Hz), and 15540 counts in the
AC detector (above a background rate of 3570 Hz). The AGILE ratemeters
light curves can be found at:
http://www.agilescienceapp.it/notices/GRB210704A_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 Notices can be found at:
https://gcn.gsfc.nasa.gov/agile_mcal.html.