TITLE: GCN CIRCULAR NUMBER: 10994 SUBJECT: GRB 100724B: gamma-ray detection by AGILE DATE: 10/07/26 14:36:30 GMT FROM: Martino Marisaldi at INAF-IASF M. Marisaldi, F. Fuschino, C. Labanti, M. Galli, A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco (INAF/IASF Bologna), E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), G. Barbiellini, F. Longo, E. Moretti (INFN Trieste), A. Giuliani, A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, G. Pucella, V. Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini (INAF/IASF Rome), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), S. Vercellone, F. D'Ammando (INAF/IASF Palermo), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Picozza, A. Morselli, E. Striani, (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Giommi, C. Pittori, F. Lucarelli, P. Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: "The AGILE Gamma-Ray Imaging Detector (GRID) and Mini-Calorimeter (MCAL) detected at gamma-ray energies the long bright GRB 100724B (Bhat, GCN 10977; Tanaka et al., GCN 10978; Golenetskii et al., GCN 10981). The GRB triggered AGILE-MCAL, sensitive in the energy range 330 keV - 100 MeV, on 24 July 2010 at 00:42:00 UT (T0). As seen by MCAL the burst has a duration (T90) of ~96 s, with observable emission up to ~T0+150 s. The GRB emission has significant detection in MCAL up to an energy of about 80 MeV. The time integrated spectrum in the time interval [T0, T0+150.0 s] can be fit in the energy range 500 keV - 80 MeV with a single powerlaw with photon index -2.09 (-0.06, +0.08) (reduced chi2 = 0.94 with 39 d.o.f.). The estimated fluence is (2.7 ± 0.2)x10-4 erg/cm2 in the same energy range. All reported errors are at the 90% confidence level. AGILE-GRID shows a definite detection above 100 MeV. Further analysis are in progress. This message may be cited."