[vsnet-grb-info 23407] LIGO/Virgo S190828j: Upper limits from AGILE-GRID observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25506
SUBJECT: LIGO/Virgo S190828j: Upper limits from AGILE-GRID observations
DATE:    19/08/28 09:07:17 GMT
FROM:    Francesco Verrecchia at ASDC  <francesco.verrecchia at ssdc.asi.it>

F. Longo (Univ. Trieste, and INFN Trieste), C. Pittori, F. Verrecchia 
(SSDC, and
INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo,
C. Casentini, G. Piano, A. Ursi (INAF/IAPS), F. Lucarelli (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 S190828j at T0 = 2019-08-28 
06:34:05.756
UT a preliminary analysis of the AGILE exposure at T0 shows that the 
Gamma-Ray
Imaging Detector (GRID) exposure covered more than 15% of the 90% c.l.
localization region (LR) (32% of 90% c.l. localization region (LR) is 
occulted
by Earth).

We performed an analysis of the GRID data in the energy range 50 MeV -
10 GeV on T0, where good exposure of the S190828j 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 7.9e-07 to 9.74e-06 erg cm^-2 s^-1, with exposure of about 36% of 
the LR
over the time interval ( T0 -2s ; T0 + 2s );
from 6.5e-07 to 6.1e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR
over the time interval ( T0s ; T0 + 5s );
from 3.39e-07 to 6e-06 erg cm^-2 s^-1, with exposure of about 34% of the LR
over the time interval ( T0s ; T0 + 10s );
from 1.3e-07 to 5.91e-06 erg cm^-2 s^-1, with exposure of about 36% of 
the LR
over the time interval ( T0s ; T0 + 100s );

A map in Galactic coordinates showing the AGILE FoV at T0 is available 
at the
site:
https://tools.ssdc.asi.it/ImgView/Agile/aitoff_MULTImap2019-08-28-4s_mod19

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