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GCN Circular 26441

LIGO/Virgo S191215w: Identification of a GW compact binary merger candidate
2019-12-15T23:04:15Z (5 years ago)
Nelson Christensen at la Cote dAzur,Nice <>
The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S191215w during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-12-15
22:30:52.333 UTC (GPS time: 1260484270.333). The candidate was found
by the GstLAL [1], CWB [2], MBTAOnline [3], and PyCBC Live [4]
analysis pipelines.

S191215w is an event of interest because its false alarm rate, as
estimated by the online analysis, is 1e-09 Hz, or about one in 31
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

Two sky maps are 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 7 minutes after the candidate
event time.
  * bayestar.fits.gz,1, an initial localization generated by BAYESTAR
[5], distributed via GCN notice about 15 minutes after the candidate
event time.

The preferred sky map at this time is bayestar.fits.gz,1. For the
bayestar.fits.gz,1 sky map, the 90% credible region is 923 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 2216 +/- 590 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] Klimenko et al. PRD 93, 042004 (2016)
  [3] Adams et al. CQG 33, 175012 (2016)
  [4] Nitz et al. PRD 98, 024050 (2018)
  [5] Singer & Price PRD 93, 024013 (2016)
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