TITLE:   GCN CIRCULAR
NUMBER:  21662
SUBJECT: LIGO/Virgo G298936: AGILE GRID observations
DATE:    17/08/23 17:54:45 GMT
FROM:    Francesco Verrecchia at ASDC, INAF-OAR  <verrecchia@asdc.asi.it>

M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M. Pilia
(INAF/OA-Cagliari), A. Bulgarelli (INAF/IASF-Bo), M. Tavani (INAF/IAPS,
and Univ. Roma Tor Vergata), C. Pittori (SSDC and INAF/OAR), G. Piano
(INAF/IAPS), A. Ursi(INAF/IAPS), I. Donnarumma (ASI), F. Longo (Univ.
Trieste and INFN Trieste), G. Minervini, A. Argan, Y. Evangelista
(INAF/IAPS), F. Lucarelli (SSDC and INAF/OAR), N. Parmiggiani, A. Zoli,
V. Fioretti, F. Fuschino (INAF/IASF-Bo), A. Trois (INAF/OA-Cagliari) M.
Marisaldi (INAF/IASF-Bo and Bergen University), A. Giuliani (INAF/IASF-Mi),
report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW event G298936 (T0 = 2017-08-23 13:13:58.518
UTC; GCN #21656), analysis of AGILE data shows that the satellite at T0 was
in the South Atlantic Anomaly (SAA). Scientific telemetry was inhibited
during the time interval (T0 -300 s; T0 + 400 s).

We performed a preliminary analysis of the AGILE Gamma-Ray Imaging Detector
(GRID) in the first interval available after the SAA, between T0 +400s and
T0 +500s. In this time interval, the GRID exposure covered nearly 55% of the
LIGO/Virgo updated (GCN #21661) localization region (LR), observed at off-axis
angles between 5 deg and 50 deg.

An analysis of the data in the energy range 50 MeV - 10 GeV in this
integration time was performed and preliminary 3-sigma upper limits (UL)
values within the accessible LIGO/Virgo LR are:
from 3.1e-0.8 to 7.6e-7 erg cm^-2 s^-1 for integration time of 100s.

These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress