TITLE: GCN CIRCULAR NUMBER: 24626 SUBJECT: LIGO-Virgo S190521g: Upper Limits from AGILE-GRID observations DATE: 19/05/21 06:34:26 GMT FROM: Francesco Verrecchia at ASDC F. Verrecchia (SSDC, and INAF-OAR), C. Casentini (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Lucarelli, C. Pittori (SSDC, and INAF-OAR), M. Cardillo (INAF/IAPS), G. Piano A. Ursi (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 S190521g at T0 = 2019-05-21 03:02:29.47 UTC (GCN #24621) a preliminary analysis of the AGILE exposure at T0 showed the S190521g 90% c.l. localization region (LR) was not exposed by the Gamma-Ray Imaging Detector (GRID), the nearest exposure in time occurred at T0-15s covering about 60% of the LR near the Galactic north pole at off-axis angles between 15 and 60 deg. We performed an analysis of the GRID data in the energy range 50 MeV - 10 GeV over three time intervals before and after T0, when good exposure of the S190521g 90% c.l. LR was available. The following preliminary GRID 3-sigma upper limit (UL) values are obtained over a large area of the exposed LR: (T0-15s; T0-5s ): from 2.7e-07 to 1.4e-06 erg cm^-2 s^-1; (T0-100s; T0 ): from 4.5e-08 to 5.4e-07 erg cm^-2 s^-1; (T0+900s; T0+1000s): from 3.0e-08 to 5.0e-07 erg cm^-2 s^-1. An image of the AGILE-GRID 10s exposure near T0 is available at the site https://tools.ssdc.asi.it/ImgView/Agile/S190521g_T0-15s_d10s_bayest_fv70a75off13 These measurements were obtained with AGILE observing a large portion of the sky in spinning mode. Additional analysis of AGILE data is in progress.