TITLE:   GCN CIRCULAR
NUMBER:  27187
SUBJECT: LIGO/Virgo S200224ca: upper limits from AGILE/MCAL observations
DATE:    20/02/25 00:30:51 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G.
Piano (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 S200224ca at T0 = 2020-02-24
22:22:34.378 (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, the S200224ca 90% c.l. localization region (LR) was totally
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 S200224ca LR, from a
minimum of 2.17E-06 erg cm^-2 to a maximum of 6.32E-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 range 0.4-1 MeV, for a 300 us integration time, from a
minimum of 1.44E-08 erg cm^-2 to a maximum of 4.39E-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.