GCN Circular 25012

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S190707q during
real-time processing of data from LIGO Hanford Observatory (H1) and
LIGO Livingston Observatory (L1) at 2019-07-07 09:33:26.181 UTC (GPS
time: 1246527224.181). The candidate was found by the MBTAOnline [1],
CWB [2], GstLAL [3], PyCBC Live [4], and SPIIR [5] analysis pipelines.

S190707q is an event of interest because its false alarm rate, as
estimated by the online analysis, is 5.3e-12 Hz, or about one in 1e4
years. The event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S190707q

The classification of the GW signal, in order of descending
probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), NSBH (<1%),
or MassGap (<1%).

Assuming the candidate is astrophysical in origin, there is strong
evidence against the lighter compact object having a mass < 3 solar
masses (HasNS: <1%). Using the masses and spins inferred from the
signal, there is strong evidence against matter outside the final
compact object (HasRemnant: <1%).

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 39 minutes after the candidate

For the bayestar.fits.gz sky map, the 90% credible region is 1375
deg2. Marginalized over the whole sky, the a posteriori luminosity
distance estimate is 810 +/- 234 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] Adams et al. CQG 33, 175012 (2016)
 ��[2] Klimenko et al. PRD 93, 042004 (2016)
 ��[3] Messick et al. PRD 95, 042001 (2017)
 ��[4] Nitz et al. PRD 98, 024050 (2018)
 ��[5] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 ��[6] Singer & Price PRD 93, 024013 (2016)