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GCN Circular 27130

LIGO/Virgo S200219ac: Identification of a GW compact binary merger candidate
2020-02-19T12:53:35Z (4 years ago)
Sarah Antier at APC <>
The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S200219ac during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2020-02-19
09:44:15.195 UTC (GPS time: 1266140673.195). The candidate was found
by the PyCBC Live [1], CWB [2], MBTAOnline [3], SPIIR [4], and GstLAL [5]
analysis pipelines.

The delay in issuing the alert was due to a software issue in the
online system.

S200219ac is an event of interest because its false alarm rate, as
estimated by the online analysis, is 1.3e-08 Hz, or about one in 2
years. The event's properties can be found at this URL:

The classification of the GW signal, in order of descending
probability, is BBH (96%), Terrestrial (4%), BNS (<1%), NSBH
(<1%) or MassGap (<1%).

Assuming the candidate is astrophysical in origin, the probability
that the lighter compact object has a mass < 3 solar masses (HasNS) is
<1%. Using the masses and spins inferred from the signal, the
probability of matter outside the final compact object (HasRemnant) is

One sky map is available at this time and can be retrieved from the
GraceDB event page:
 �� * bayestar.fits.gz, an updated localization generated by BAYESTAR
[6], distributed via GCN notice about 2 hours after the candidate.

The preferred sky map at this time is bayestar.fits.gz. For the
bayestar.fits.gz sky map, the 90% credible region is 1251 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 1510 +/- 405 Mpc (a posteriori mean +/- standard deviation).

For further information about analysis methodology and the contents of
this alert, refer to the LIGO/Virgo Public Alerts User Guide

 ��[1] Nitz et al. PRD 98, 024050 (2018)
 ��[2] Klimenko et al. PRD 93, 042004 (2016)
 ��[3] Adams et al. CQG 33, 175012 (2016)
 ��[4] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 ��[5] Messick et al. PRD 95, 042001 (2017)
 ��[6] Singer & Price PRD 93, 024013 (2016)
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