[vsnet-grb-info 21981] LIGO-Virgo S190408an: further AGILE GRID observations after T0

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24080
SUBJECT: LIGO-Virgo S190408an: further AGILE GRID observations after T0
DATE:    19/04/09 13:56:45 GMT
FROM:    Fabrizio Lucarelli at SSDC/INAF-OAR  <fabrizio.lucarelli at ssdc.asi.it>

F. Lucarelli, 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),
A. Bulgarelli, 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 trigger event S190408an at T0 = 2019-04-08 18:18:02 (UT)
(GCN #24069) we performed a further analysis of the AGILE Gamma-Ray Imaging Detector
(GRID) data after the trigger time.

An analysis of the data in the energy range 30 MeV - 10 GeV was performed over the time
interval T0+200s -- T0+300s, where full coverage of the majority of the localisation
region (>95%) was reached.

Preliminary GRID values of 3-sigma upper limits (UL) obtained within the accessible
LIGO/Virgo 90% c.l. localization region over this time interval are in the range:

from 2.5e-07 to 3.5e-07 erg cm^-2 s^-1 for an integration time of 100s.

These UL values are compatible with those obtained for an integration time of 100s
before T0, and reported in the previous AGILE GRID GCN #24071.

These measurements were obtained with AGILE observing a large portion of the sky
in spinning mode.