TITLE: GCN CIRCULAR NUMBER: 24442 SUBJECT: LIGO/Virgo S190510g: Identification of a GW compact binary merger candidate DATE: 19/05/10 05:51:38 GMT FROM: Eric Howell at Aus.Intl.Grav.Res.Centre/UWA The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S190510g during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-05-10 02:59:39.292 UTC (GPS time: 1241492397.292). The candidate was found by the GstLAL [1] analysis pipeline. S190510g is an event of interest because its false alarm rate, as determined by the online analysis, is 8.4e-10 Hz, or about one in 37 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S190510g The classification of the GW signal, in order of descending probability, is BNS (98%), Terrestrial (2%), NSBH (<1%), BBH (<1%), or MassGap (<1%). Assuming the candidate is astrophysical in origin, there is strong evidence for the lighter compact object having a mass < 3 solar masses (HasNS: >99%). Using the masses and spins inferred from the signal, there is strong evidence for matter outside the final compact object (HasRemnant: >99%). One skymap 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 an hour after the candidate For the bayestar.fits.gz skymap, the 90% credible region is 3462 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 269 +/- 108 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)