GCN Circular 24638
Subject
LIGO/Virgo S190521r: Upper limits from AGILE-GRID observations
Date
2019-05-21T11:52:18Z (6 years ago)
From
Francesco Verrecchia at ASDC <francesco.verrecchia@ssdc.asi.it>
F. Verrecchia (SSDC, and INAF-OAR), C. Casentini (INAF/IAPS), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata),�� F. Lucarelli, C. Pittori
(SSDC, and
INAF-OAR), M. Cardillo, G. Piano A. Ursi (INAF/IAPS), 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 S190521r at T0 = 2019-05-21
07:43:59.463
UTC (GCN #24632) a preliminary analysis of the AGILE exposure at T0 showed
the S190521g 90% c.l. localization region (LR) was not exposed by the
Gamma-Ray
Imaging Detector (GRID). The closest exposure in time occurred at T0-15s
covering about 40% of the LR at off-axis angles between 50 and 60 deg.
We performed an analysis of the GRID data in the energy range 50 MeV -
10 GeV
over three time intervals before and after T0, when good exposure of
the S190521r 90% c.l. LR was available.
The following preliminary GRID 3-sigma upper limit (UL) values are obtained
over a large area of the exposed LR:
(T0-15s; T0-5s ): from 1.3e-06 to 3.0e-06 erg cm^-2 s^-1, with exposure of
about 40% of the LR;
(T0-100s; T0 ): from 3.5e-08 to 4.5e-07 erg cm^-2 s^-1, with exposure of
about 60% of the LR;
(T0+200s; T0+300s): from 5.2e-08 to 6.4e-07 erg cm^-2 s^-1, with exposure of
about 80% of the LR.
An image of the AGILE-GRID 10s exposure near T0 is available at the site
https://tools.ssdc.asi.it/ImgView/Agile/S190521r_T0-15s_d10s_FM_UL-E50offbm14
These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.