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GCN Circular 20489

LIGO/Virgo G270580: AGILE MCAL and Super-AGILE Observations
2017-01-20T21:57:23Z (7 years ago)
Francesco Verrecchia at ASDC, INAF-OAR <>
F. Lucarelli, F. Verrecchia (ASDC and INAF/OAR), A. Ursi (INAF/IAPS), Y.
Evangelista (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), F. Fuschino (INAF/IASF-Bo), I. Donnarumma (INAF/IAPS), G.
Minervini (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University),
A. Bulgarelli, V. Fioretti (INAF/IASF-Bo), C. Pittori (ASDC and
INAF/OAR), G. Piano, P. Munar-Adrover, A. Argan (INAF/IAPS), M. Cardillo
(INAF/OA-Arcetri and INAF/IAPS), A. Giuliani (INAF/IASF-Mi), M. Pilia, A.
Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste),
report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW event G270580 (GCN #20486) at
T0 = 2017-01-20 12:30:59.350 UTC, the analysis of the AGILE data near T0
shows that the onboard data acquisition was interrupted due to the
passage over the South Atlantic Anomaly (SAA), which covered the time
interval (T0 - 280; T0 + 216) s.

A preliminary AGILE-GW data processing identified two Mini-Calorimeter
(MCAL) data acquisitions before and after the SAA passage. The first
data interval (following an internal trigger) started at T1 = 12:26:14
UTC, and ended at T2 = 12:26:22 UTC. The second one, started at
T3 = 12:36:16 UTC, and ended at T4 = 12:36:24 UTC. An analysis of these
data does not reveal any significant transient event in the energy range
0.4-100 MeV. A preliminary three-sigma upper limit (UL) is obtained for
a 1 s integration time at different celestial positions within the
accessible G270580 localization region, for a typical fluence of 8.8e-7
erg cm^-2, in the 400-10000 keV energy range assuming a spectral photon
index of 1.4.

The Super-Agile (SA) detector had a partial coverage of the G270580
localization region at T0. No significant detection was obtained in the
SA light curve (20-60 keV), for a stable background within +/- 100 s
from T0. SA is an X-ray coded mask instrument with 40x40 deg field of
view at half-sensitivity.

Furthermore, a search in the AGILE anticoincidence (AC) and GRID
ratemeters data did not produce any significant detection.

The GRID large-FoV (2.5 sr) imaging instrument had no exposure near T0
of the G270580 localization region. The GRID data analysis in the energy
range 30 MeV - 10 GeV is in progress, and the results will be reported
in a following GCN.
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