[vsnet-grb-info 23720] LIGO/Virgo S190923y: No counterpart candidates in AGILE-MCAL observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25819
SUBJECT: LIGO/Virgo S190923y: No counterpart candidates in AGILE-MCAL observations
DATE:    19/09/23 15:05:54 GMT
FROM:    Claudio Casentini at INAF-IAPS  <claudio.casentini at inaf.it>

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

In response to the LIGO/Virgo GW event S190923y at T0 = 2019-09-23
12:55:59.646 (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 60% of the S190923y 90% c.l. localization region (LR) 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 S190923y LR, from a minimum of 1.08E-06 erg cm^-2 to a maximum
of 7.70E-06 erg cm^-2 (assuming as spectral model a single power law with
photon index 1.5).

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.