TITLE: GCN CIRCULAR NUMBER: 24457 SUBJECT: LIGO-Virgo S190510g: AGILE GRID observations DATE: 19/05/10 16:27:22 GMT FROM: Francesco Verrecchia at ASDC F. Verrecchia (SSDC, and INAF-OAR), A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Lucarelli, C. Pittori (SSDC, and INAF-OAR), M. Cardillo, C. Casentini, G. Piano (INAF/IAPS), 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 S190510g at T0 = 2019-05-10 02:59:39.292 UTC (GCN #24442 including an updated localization) a preliminary analysis of the AGILE exposure at T0 showed that about 60% of the S190510g 90% c.l. localization region (LR) was exposed at off-axis angles between 25 and 75 deg by the Gamma-Ray Imaging Detector (GRID). We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV over three time intervals before and after T0, where good exposure of the S190510g 90% c.l. LR was available. No candidate gamma-ray transient was detected. The following preliminary GRID 3-sigma upper limit (UL) values are obtained: (T0 - 2s; T0 + 2s): from 7.4e-07 to 1.7e-06 erg cm^-2 s^-1 (T0 - 10s; T0 + 10s): from 1.5e-07 to 3.5e-07 erg cm^-2 s^-1 (T0; T0 + 100s): from 4.2e-08 to 1.8e-07 erg cm^-2 s^-1 An image of the AGILE-GRID exposure near T0 is available at the site https://tools.ssdc.asi.it/ImgView/Agile/S190510g_d4s_FM_UL-E50bemod8 These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress.