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LIGO-Virgo S190408an

GCN Circular 24063

Subject
LIGO-Virgo S190408an: AGILE MCAL observations
Date
2019-04-08T20:42:39Z (6 years ago)
From
Fabrizio Lucarelli at SSDC/INAF-OAR <fabrizio.lucarelli@ssdc.asi.it>
F. Lucarelli (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano, 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 S190408an at T0 = 2019-04-08 18:18:02 (UT), a preliminary analysis of the AGILE MiniCalorimeter (MCAL) data found no event candidates within a time interval covering -15 / + 8 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 S190408an localization region, from a minimum of 1.3E-06 erg cm^-2 to a maximum of 2.2E-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.





==========================================

Fabrizio Lucarelli, PhD

ASI Space Science Data Center (SSDC/ASDC) & INAF-OAR

Via del Politecnico snc

00133 Rome, Italy

Tel. +39 068567404

GCN Circular 24067

Subject
LIGO-Virgo S190408an: HAWC follow-up
Date
2019-04-08T21:08:25Z (6 years ago)
From
Israel Martinez-Castellanos at UMD/HAWC <imc@umd.edu>
I. Martinez-Castellanos (University of Maryland, College Park) report on
behalf of the HAWC Collaboration:

The HAWC Collaboration performed a follow-up of the gravitational wave
trigger S190408an. At the time of the trigger the HAWC local zenith was
oriented toward (��, ��) = (13.9��, 19.0��). 80% of the GW candidate sky
location probability fell within our observable field (0-45 deg zenith
angle).

We performed a search for a short timescale emission using 6 sliding time
windows (dt = 0.3s, 1s, 3s, 10, 30s and  100s), shifted forward in time by
20% of their width. We searched in a timescale-dependent time period, from
t0-5dt to t0+10dt, where t0 is the time of the GW trigger. No significant
gamma-ray detection above the steady-state cosmic-ray background was
observed.

The sensitivity of this analysis is greatly dependent on energy and zenith
angle. For reference, it has a 5sigma detection sensitivity to a 1s (100s)
burst with a fluence of 3x10^-7 erg/cm^2 to 2x10^-5 erg/cm^2 (2x10^-6
erg/cm^2 to 8x10^-5 erg/cm^2) in the 0.3-1TeV energy range, depending on
the zenith angle.

HAWC is a TeV gamma ray water Cherenkov array located in the state of
Puebla, Mexico. It is sensitive to the energy range ~0.3-100TeV, and
monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2
sr.

GCN Circular 24071

Subject
LIGO-Virgo S190408an: AGILE GRID observations
Date
2019-04-09T00:14:47Z (6 years ago)
From
Fabrizio Lucarelli at SSDC/INAF-OAR <fabrizio.lucarelli@ssdc.asi.it>
F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano, A. Ursi (INAF/IAPS), 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 trigger event S190408an at

T0 = 2019-04-08 18:18:02 (UT)  (GCN #24069)  we performed an

analysis of the AGILE Gamma-Ray Imaging Detector (GRID) data.


At LIGO/Virgo trigger time (T0) the GRID exposure did not optimally cover the

LIGO/Virgo localization region.


An analysis of the data in the energy range 30 MeV - 10 GeV was performed

over the time intervals T0-300s -- T0-200s, where full coverage of the majority of the

localisation region was reached.


Preliminary values of 3-sigma upper limits (UL) obtained within the accessible

LIGO/Virgo 90% c.l. localization region over this time interval are in the range:


from 2.0e-07 to 6.5e-07 erg cm^-2 s^-1 for an integration time of 100s.


For an integration time of 200s which includes T0, preliminary 3-sigma ULs are

in the range:


from 5.0e-08 to 3.0e-07 erg cm^-2 s^-1,


with a lower localization region coverage of about 80%.

These measurements were obtained with AGILE observing a large portion of the

sky in spinning mode. Additional analysis of AGILE data is in progress.

GCN Circular 24080

Subject
LIGO-Virgo S190408an: further AGILE GRID observations after T0
Date
2019-04-09T13:56:45Z (6 years ago)
From
Fabrizio Lucarelli at SSDC/INAF-OAR <fabrizio.lucarelli@ssdc.asi.it>
F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS,
and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano, A. Ursi (INAF/IAPS),
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 trigger event S190408an at T0 = 2019-04-08 18:18:02 (UT)
(GCN #24069) we performed a further analysis of the AGILE Gamma-Ray Imaging Detector
(GRID) data after the trigger time.

An analysis of the data in the energy range 30 MeV - 10 GeV was performed over the time
interval T0+200s -- T0+300s, where full coverage of the majority of the localisation
region (>95%) was reached.

Preliminary GRID values of 3-sigma upper limits (UL) obtained within the accessible
LIGO/Virgo 90% c.l. localization region over this time interval are in the range:

from 2.5e-07 to 3.5e-07 erg cm^-2 s^-1 for an integration time of 100s.

These UL values are compatible with those obtained for an integration time of 100s
before T0, and reported in the previous AGILE GRID GCN #24071.

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

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