LIGO-Virgo S190421ar

A. Ursi, M. Cardillo (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), C. Casentini, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, 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 S190421ar at T0 = 2019-04-21
21:38:56 (UT), a preliminary analysis of the AGILE minicalorimeter (MCAL)
data found no event candidates within a time interval covering -/+ 1000 sec
from the LIGO-Virgo T0.

Two-sigma upper limits (ULs) are obtained for a 1 s integration time at
different celestial positions within the accessible S190421ar 90% c.l.
localization region, from a minimum of 1.30E-06 erg cm^-2 to a maximum of
3.02E-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.

M. Cardillo (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), A. Ursi 
(INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), C. 
Casentini, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori (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 S190421ar T0 = 2019-04-21 
21:38:56 (UTC; GCN #24141
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 ), 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 -600 s; T0 + 400 s).

We performed a preliminary analysis of the AGILE Gamma-Ray Imaging 
Detector (GRID) in the first interval available after the SAA, between 
T0 +450s and T0+550s. In this time interval, the GRID exposure covered 
nearly 55% of the LIGO/Virgo localization region (LR), observed at 
off-axis angles between 15 deg and 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 accessible LIGO/Virgo LR are:
from 4.9e-8 erg cm^-2 s^-1 to 3.0e-7 erg cm^-2 s^-1 for integration time 
of 100s.

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

S. Xiao, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, 
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

In response to the LIGO-Virgo GW event S190421ar T0 = 2019-04-21 
21:38:56 (UTC; GCN #24141
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 ), analysis of HXMT/HE data shows that the 
satellite at T0 was in the South Atlantic Anomaly (SAA).

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.