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GCN Circular 26303

LIGO/Virgo S191129u: Identification of a GW compact binary merger candidate
2019-11-29T14:38:28Z (5 years ago)
Leo Singer at GSFC <>
The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S191129u during
real-time processing of data from LIGO Hanford Observatory (H1) and
LIGO Livingston Observatory (L1) at 2019-11-29 13:40:29.197 UTC (GPS
time: 1259070047.197). The candidate was found by the GstLAL [1],
MBTAOnline [2], SPIIR [3], and PyCBC Live [4] analysis pipelines.

S191129u is an event of interest because its false alarm rate, as
estimated by the online analysis, is 2.7e-35 Hz, or about one in 1e27
years. The event's properties can be found at this URL:

The classification of the GW signal, in order of descending
probability, is BBH (99%), Terrestrial (1%), BNS (<1%), MassGap (<1%),
or NSBH (<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,0, an initial localization generated by BAYESTAR
[5], distributed via GCN notice about 42 minutes after the candidate
event time.

For the bayestar.fits.gz,0 sky map, the 90% credible region is 1011
deg2. Marginalized over the whole sky, the a posteriori luminosity
distance estimate is 763 +/- 200 Mpc (a posteriori mean +/- standard

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

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