[vsnet-grb-info 22420] LIGO-Virgo S190512at: AGILE GRID observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24519
SUBJECT: LIGO-Virgo S190512at: AGILE GRID observations
DATE:    19/05/13 15:40:22 GMT
FROM:    Carlotta Pittori at ASI SSDC, INAF-OAR  <carlotta.pittori at ssdc.asi.it>

C. Pittori(SSDC, and INAF/OAR), A. Ursi(INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. Casentini, G. Piano, M. Cardillo (INAF/IAPS), F. Lucarelli, F. Verrecchia(SSDC, and INAF/OAR), A. Bulgarelli, 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 S190512at T0 = 2019-05-12 18:07:14.422 UTC (GCN #24503), analysis of AGILE data shows that the satellite at T0 was in the South Atlantic Anomaly (SAA). Scientific telemetry was inhibited during the time interval (T0 -13 s; T0 + 834 s).

We performed a preliminary analysis of the AGILE Gamma-Ray Imaging Detector (GRID) in the first interval available after the SAA, between T0 +840s and T0+940s. In this time interval, due to Earth occultation and Solar Panel constraints, the GRID exposure covered only about 1% of the LIGO/Virgo 90% c.l. localization region (LR), observed at off-axis angles of about 60 deg.

An analysis of the data in the energy range 50 MeV - 10 GeV in this integration time was performed, and preliminary 3-sigma upper limits (UL) values within the small accessible LIGO/Virgo localization region are:
from 8.9e-7 erg cm^-2 s^-1 to 1.0e-6 erg cm^-2 s^-1 for an integration time of 100s.

We also performed a search for a transient counterpart in the time window from T0 + 1 ks to T0 + 10 ks. In this time interval due to Solar Panel constraints, the GRID exposure covered about 40% of the LR, observed at off-axis angles from about 55 to 100 deg. Preliminary 3-sigma upper limits values are:
from 2.8e-9 erg cm^-2 s^-1 to 1.0e-8 erg cm^-2 s^-1 for an integration time of 9 ks.

An image of the AGILE-GRID exposure of S190512at in the time window from T0 + 1 ks to T0 + 10 ks is available at the site:
https://tools.ssdc.asi.it/ImgView/Agile/AGILE_exp_T0p1k-T0p10k_S190512at9

These measurements were obtained with AGILE observing a large portion of the sky in spinning mode.