[vsnet-grb-info 21972] LIGO-Virgo S190408an: AGILE GRID observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24071
SUBJECT: LIGO-Virgo S190408an: AGILE GRID observations
DATE:    19/04/09 00:14:47 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 an

analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data.


At LIGO/Virgo trigger time (T0) the GRID exposure did not optimally cover the

LIGO/Virgo localization region.


An analysis of the data in the energy range 30 MeV - 10 GeV was performed

over the time intervals T0-300s -- T0-200s, where full coverage of the majority of the

localisation region was reached.


Preliminary 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 2.0e-07 to 6.5e-07 erg cm^-2 s^-1 for an integration time of 100s.


For an integration time of 200s which includes T0, preliminary 3-sigma ULs are

in the range:


from 5.0e-08 to 3.0e-07 erg cm^-2 s^-1,


with a lower localization region coverage of about 80%.

These measurements were obtained with AGILE observing a large portion of the

sky in spinning mode. Additional analysis of AGILE data is in progress.