TITLE: GCN CIRCULAR NUMBER: 9343 SUBJECT: AGILE detection of GRB 090510 DATE: 09/05/10 19:38:52 GMT FROM: Marco Feroci at IASF/INAF F. Longo, E. Moretti, G. Barbiellini, E. Vallazza (INFN Trieste), A. Giuliani (INAF/IASF Milan), S. Cutini, C. Pittori (ASDC) M. Marisaldi, A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Galli (INAF/IASF Bologna), A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), Y. Evangelista, E. Del Monte, M. Feroci, I. Donnarumma, L. Pacciani, P. Soffitta, E. Costa, F. Lazzarotto, I. Lapshov, M. Rapisarda(INAF/IASF Rome), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), S. Vercellone (INAF/IASF Palermo), M. Tavani, G. Pucella, F. D'Ammando, V.Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini (INAF/IASF Rome), P. Picozza, A. Morselli (INFN Roma-2), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), A. Rappoldi, P. Cattaneo (INFN Pavia) and P. Giommi, P. Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: AGILE detected the remarkable short GRB 090510 (Hoversten et al. GCN #9331, Ohno et al. GCN #9334) at approximately 61 degrees off-axis. An analysis of AGILE-GRID data shows an above 5-sigma detection of gamma-ray emission above 100 MeV. The gamma-ray lightcurve above 100 MeV shows emission during both the prompt phase and during a "delayed" phase. Also the Mini-Calorimeter detected a very significant and structured event lasting ~200 msec with emission well above 3 MeV. The burst triggered also SuperAGILE, although outside the field of view. This is the first short GRB with emission above 100 MeV detected by AGILE.