TITLE:   GCN CIRCULAR
NUMBER:  26715
SUBJECT: LIGO/Virgo S200112r: Identification of a GW compact binary merger candidate
DATE:    20/01/12 16:27:18 GMT
FROM:    Erik Katsavounidis at MIT  <kats@ligo.mit.edu>

LIGO/Virgo S200112r: Identification of a GW compact binary merger candidate

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S200112r during
real-time processing of data from LIGO Livingston Observatory (L1) and
Virgo Observatory (V1) at 2020-01-12 15:58:38.094 UTC (GPS time:
1262879936.094). The candidate was found by the GstLAL [1] analysis
pipeline.

S200112r is an event of interest because its false alarm rate, as
estimated by the online analysis, is 1.3e-11 Hz, or about one in 1e3
years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S200112r

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
<1%.

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
[2], distributed via GCN notice about 2 minutes after the candidate
event time.
  * bayestar.fits.gz,1  -- identical to bayestar.fits.gz,0

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 6199 deg2.
Marginalized over the whole sky, the a posteriori luminosity distance
estimate is 1136 +/- 320 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
<https://emfollow.docs.ligo.org/userguide/>.

  [1] Messick et al. PRD 95, 042001 (2017)
  [2] Singer & Price PRD 93, 024013 (2016)