TITLE:   GCN CIRCULAR
NUMBER:  33894
SUBJECT: LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
DATE:    23/05/30 08:00:31 GMT
FROM:    Francesco Verrecchia at SSDC,INAF-OAR <francesco.verrecchia@ssdc.asi.it>

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

In response to the LIGO/Virgo/KAGRA GW event S230529y at
T0 = 2023-05-29 18:15:00.89 (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/KAGRA T0.

At the T0, about 60% of the S230529y 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 S230529y
localization region in the energy range 0.4-1 MeV, from a minimum
of 1.5E-06 erg cm^-2 to a maximum of 3.1E-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, from a minimum of 1.1E-08 erg cm^-2
to a maximum of 2.1E-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.