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GCN Circular 20375

Subject
LIGO/Virgo G268556: AGILE MCAL and Super-AGILE Observations
Date
2017-01-05T22:51:15Z (7 years ago)
From
Francesco Verrecchia at ASDC, INAF-OAR <verrecchia@asdc.asi.it>
M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Ursi (INAF/IAPS),
F. Fuschino (INAF/IASF-Bo), Y. Evangelista, I. Donnarumma (INAF/IAPS),
F. Verrecchia (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), M. Marisaldi
(INAF/IASF-Bo and Bergen University), A. Bulgarelli, A. Zoli
(INAF/IASF-Bo), C. Pittori, F. Lucarelli (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 G268556 at T0 = 2017-01-04
10:11:58.599 UTC, a preliminary analysis of the AGILE-GW data processing
procedure identified a Mini-Calorimeter (MCAL) data acquisition within
the time interval close to T0. The MCAL full telemetry acquisition
(following an internal trigger) started at T1 = 10:11:47.397 UTC and
ended at T2 = 10:11:59.997 UTC. The acquisition lasted 12.6 sec and
included the T0 time of interest. An analysis of these data does not
reveal any significant transient event in the energy range 0.4-100 MeV.
Three-sigma upper limits (UL) are obtained for a 1 s integration time at
different celestial positions within the accessible G268556 localization
region, from a minimum of 5.45e-7 erg cm^-2 to a maximum of 6.18e-7 erg
cm^-2, in the 400-10000 keV energy range. The AGILE-MCAL detector has a
full solid angle acceptance, and is operational in the range 0.4 - 100
MeV. The MCAL current trigger rate is on average ~ 0.15 every 20 sec.

The Super-Agile (SA) detector had a partial coverage of the G268556
localization region at T0 (within 1s), that was observed between 0 and
30 deg off-axis. No significant detection was obtained in the SA light
curve (20-60 keV), for a stable background within +/-100s from T0. The
3-sigma UL has been derived for a 1 s integration time, and varies between
1.5e-8 erg cm^-2 (for an on-axis position) and 6.6e-8 erg cm^-2 (for a 30
degrees off-axis position). 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 exposure near T0 for a
significant fraction of the G268556 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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