GCN Circular 25884

LIGO/Virgo S190930s: no counterpart candidates in AGILE-GRID observations

M. Cardillo (INAF/IAPS),� F. Verrecchia (SSDC, and INAF/OAR), F. Longo 
(Univ. Trieste, and INFN Trieste), M. Tavani (INAF/IAPS, and Univ. Roma 
Tor Vergata), C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli, 
C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, N. 
Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari),� report on 
behalf of the AGILE Team:

In response to the LIGO/Virgo GW event S190930s at T0 = 2019-09-30 
13:35:41 (UT), a preliminary analysis of the AGILE exposure at T0 shows 
that the Gamma-Ray Imaging Detector (GRID) exposure covered about 27% of 
the 90% c.l. localization region (LR) (40% of 90% c.l. LR is occulted by 
Earth) at an off-axis angle of about 5 degrees.

We performed an analysis of the GRID data in the energy range 50 MeV - 
10 GeV on T0, where good exposure of the S190930s 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 1.0e-06 to 4.9e-06 erg cm^-2 s^-1, with exposure of about 27% of 
the LR over the time interval ( T0 -2s ; T0 + 2s );
- from 8.4e-07 to 2.5e-06 erg cm^-2 s^-1, with exposure of about 26% of 
the LR over the time interval ( T0s ; T0 + 10s );
- from 1.4e-07 to 1.6e-06 erg cm^-2 s^-1, with exposure of about 26% of 
the LR over the time interval ( T0 ; T0 + 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.