[vsnet-grb-info 23606] LIGO/Virgo S190910d: no counterpart candidates in AGILE-GRID observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25705
SUBJECT: LIGO/Virgo S190910d: no counterpart candidates in AGILE-GRID observations
DATE:    19/09/10 08:23:57 GMT
FROM:    Giovanni Piano at INAF-IAPS  <giovanni.piano at inaf.it>

G. Piano, C. Casentini (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma
Tor Vergata), M. Cardillo, A. Ursi (INAF/IAPS), F. Lucarelli, C. Pittori,
F. Verrecchia (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 S190910d at T0 = 2019-09-10
01:26:19.243 UTC a preliminary analysis of the AGILE exposure at T0 shows
that the Gamma-Ray Imaging Detector (GRID) exposure covered the 11% of the
90% c.l. localization region (LR) (19% 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.

No candidate gamma-ray transient was detected.

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

- from 7.5e-07 to 4.0e-06 erg cm^-2 s^-1, with exposure of about 11% of the
LR over the time interval (T0 - 2 s; T0 + 2 s);
- from 6.1e-07 to 3.2e-06 erg cm^-2 s^-1, with exposure of about 11% of the
LR over the time interval (T0; T0 + 5 s);
- from 3.1e-07 to 2.3e-06 erg cm^-2 s^-1, with exposure of about 11% of the
LR over the time interval (T0; T0 + 10 s);
- from 1.1e-07 to 1.6e-06 erg cm^-2 s^-1, with exposure of about 21% of the
LR over the time interval (T0; 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.