[vsnet-grb-info 25042] LIGO/Virgo S200219ac: upper limits from AGILE/GRID observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27141
SUBJECT: LIGO/Virgo S200219ac: upper limits from AGILE/GRID observations
DATE:    20/02/19 17:42:29 GMT
FROM:    Francesco Verrecchia at SSDC,INAF-OAR  <francesco.verrecchia at ssdc.asi.it>

F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS,
and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano (INAF/IAPS),
F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N.
Parmiggiani (INAF/OAS-Bologna), M. Pilia (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 S200219ac at T0 = 2020-02-19
09:44:15.195 UTC a preliminary analysis of the AGILE exposure at T0 shows
that the Gamma-Ray Imaging Detector (GRID) exposure covered less than 10% of
the 90% c.l. localization region (LR; 40% of the LR is occulted by Earth).

We performed an analysis of the GRID data in the energy range 50 MeV - 10
GeV at T0, where good exposure of the S200219ac 90% c.l. LR was available.

No candidate gamma-ray transient was detected.

The following preliminary GRID values of 3-sigma upper limit (UL) are
obtained:

from 1.7e-06 to 9.6e-06 erg cm^-2 s^-1, with exposure of about 14% of the LR
over the time interval (T0 s ; T0 + 10 s);
from 3.8e-08 to 2.0e-06 erg cm^-2 s^-1, with exposure of about 48% of the LR
over the time interval (T0 s ; T0 + 100 s);

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