TITLE: GCN CIRCULAR NUMBER: 25012 SUBJECT: LIGO/Virgo S190707q: Identification of a GW compact binary merger candidate DATE: 19/07/07 10:41:43 GMT FROM: Sarah Antier at APC 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 .  [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)