[vsnet-grb-info 28092] GRB 210610B: AGILE detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30195
SUBJECT: GRB 210610B: AGILE detection
DATE:    21/06/11 09:09:32 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi at gmail.com>

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), 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,  (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), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:

The AGILE satellite detected the long GRB 210610B at T0 = 2021-06-10
19:51:32 s (UTC), reported by Swift (GCNs #30170, #30189).

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 30 s and
it released a total number of 2340 counts in the SA detector (above a
background rate of 65 Hz), 37190 counts in the MCAL detector (above a
background rate of 1280 Hz), and 110300 counts in the AC detector (above a
background rate of 3800 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB210610B_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition, from T1 = 2021-06-10 19:51:22.88 s +/- 0.01 (UTC) to T2 =
2021-06-10 19:51:40.27 +/- 0.01 s (UTC), and released 11740 counts in the
detector, above a background rate of 525 Hz. The MCAL light curve can be
found at:
http://www.agilescienceapp.it/notices/073428_GRB_MCAL_550439491.834857.png
. The time-integrated spectrum between T1 and T2 can be fitted in the
energy range 0.4-5 MeV with a power law model with ph.ind. -2.9
-0.33/+0.40. The fit results in a reduced chi-squared of 0.95 (36 d.o.f.)
and a fluence of 8.06e-06 ergs/cm^2 (90% confidence level), in the same
energy range.

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.