TITLE: GCN CIRCULAR NUMBER: 21700 SUBJECT: LIGO/Virgo G299232: AGILE MCAL detection of a short gamma-ray candidate DATE: 17/08/25 17:42:16 GMT FROM: Francesco Verrecchia at ASDC, INAF-OAR M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC and INAF/OAR), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), G. Piano (INAF/IAPS),A. Bulgarelli (INAF/IASF-Bo), C. Pittori (SSDC and INAF/OAR), A.Ursi (INAF/IAPS),I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste),G. Minervini, A. Argan, Y. Evangelista (INAF/IAPS), F. Lucarelli (SSDC and INAF/OAR), N. Parmiggiani, A. Zoli, V. Fioretti, F. Fuschino (INAF/IASF-Bo), A. Trois (INAF/OA-Cagliari) M. Marisaldi (INAF/IASF-Bo and Bergen University), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: In response to the LIGO/Virgo GW event G299232 (T0=2017-08-25 13:13:37.983 UT; GCN #21693), we performed a preliminary AGILE Mini-CALorimeter (MCAL) data analysis on the time interval T0 -/+100s. In the nearest data acquisition starting at T1=T0+45s we detected a short burst occurring about at T0+47s which triggered both the on-board 16 ms and 64 ms timescale hardware logics. The MCAL light curve shows a sharp single peak that lasted about 1 sec and has a total number of ~1333 counts above 400 keV in the detector, above an average background rate of 614 counts/s. Additional analysis of AGILE MCAL data is in progress, to further verify possible spurious contaminations of this detection. The AGILE-MCAL detector has a full solid angle acceptance, and is operational in the range 0.4 - 100 MeV. The MCAL current trigger rate is on average ~ 0.15 every 20 sec.