GCN Circular 35024

L. Foffano (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M. Cardillo, G. Piano (INAF/IAPS), A. Ursi (ASI and INAF/IAPS), L. Baroncelli, A. Bulgarelli, A. Ciabattoni, A. Di Piano, V. Fioretti, G. Panebianco, N. Parmiggiani (INAF/OAS-Bologna), M. Pilia (INAF/OA-Cagliari), P.W. Cattaneo (INFN Pavia), F. Cutrona (Univ. Milano Bicocca), F. Longo (Univ. Trieste, and INFN Trieste), report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW event S231113bw at T0 = 2023-11-13 20:04:17.06 (UT), a preliminary analysis of the AGILE minicalorimeter (MCAL) triggered data found no event candidates within a time interval covering -/+ 15 sec from the LIGO/Virgo T0.

At the T0, about 65% of the S231113bw 90% c.l. localization region was accessible to the AGILE MCAL.

Three-sigma upper limits (ULs) are obtained for a 1 s integration time at different celestial positions within the accessible S231113bw localization region in the 0.4-1 MeV energy range, from a minimum of 1.3E-06 erg cm^-2 to a maximum of 7.3E-06 erg cm^-2 (assuming as spectral model a single power-law with photon index 1.5).

An independent procedure based on photon counting statistics provides UL fluences in the same band, for a 300 microseconds integration time, from a minimum of 1.0E-08 erg cm^-2 to a maximum of 4.4E-08 erg cm^-2.

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.