[vsnet-grb-info 23017] LIGO/Virgo S190720a: AGILE-MCAL observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25116
SUBJECT: LIGO/Virgo S190720a: AGILE-MCAL observations
DATE:    19/07/20 05:02:11 GMT
FROM:    Claudio Casentini at INAF-IAPS  <claudio.casentini at inaf.it>

C.Casentini (INAF/IAPS),  F.Lucarelli (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), M.Cardillo, G.Piano, A.Ursi
(INAF/IAPS), F.Verrecchia, 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 S190720a at T0 = 2019-07-20
00:08:36.747 (UT), a preliminary analysis of the AGILE Minicalorimeter
(MCAL) triggered data found no event candidate at T0.

Three-sigma upper limits (ULs) are obtained for a 1 sec integration time at
T0 for different celestial positions within the accessible 90% c.l.
localization region (LR) of S190720a (almost 65% of the LR), from a minimum
of 1.39E-06 erg cm^-2 to a maximum of 5.02E-06 erg cm^-2 (assuming as
spectral model a single power law with photon index 1.5).

We notice an MCAL trigger event 2.53 sec after T0 in the 32 msec lightcurve
with a S/N of 5.1. We are assessing the statistical significance of this
feature.

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.