TITLE: GCN CIRCULAR NUMBER: 24922 SUBJECT: LIGO/Virgo S190630ag: Identification of a GW compact binary merger candidate DATE: 19/06/30 19:57:47 GMT FROM: Brandon Piotrzkowski at U of Wisconsin-Milwaukee The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190630ag during real-time processing of data from LIGO Livingston Observatory (L1) and Virgo Observatory (V1) at 2019-06-30 18:52:05.180 UTC (GPS time: 1245955943.180). The candidate was found by the GstLAL [1] analysis pipeline. S190630ag is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.4e-13 Hz, or about one in 1e5 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190630ag The classification of the GW signal, in order of descending probability, is BBH (94%), MassGap (5%), NSBH (<1%), Terrestrial (<1%), or BNS (<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 [2], distributed via GCN notice about 3 minutes after the candidate The preferred sky map at this time is bayestar.fits.gz, with 90% credible region of 8493 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1059 +/- 307 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] Messick et al. PRD 95, 042001 (2017) [2] Singer & Price PRD 93, 024013 (2016)