TITLE: GCN CIRCULAR NUMBER: 26182 SUBJECT: LIGO/Virgo S191105e: Identification of a GW compact binary merger candidate DATE: 19/11/06 18:24:36 GMT FROM: Leo Singer at GSFC The LIGO Scientific Collaboration and the Virgo Collaboration report: We identified the compact binary merger candidate S191105e during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-11-05 14:35:21.933 UTC (GPS time: 1256999739.933). The candidate was found by the PyCBC Live [1], SPIIR [2], and GstLAL [3] analysis pipelines. The preliminary alert was delayed by approximately one day due to a GraceDB authentication issue. S191105e is an event of interest because its false alarm rate, as estimated by the online analysis, is 2.3e-08 Hz, or about one in 1 year, 4 months. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S191105e The classification of the GW signal, in order of descending probability, is BBH (95%), Terrestrial (5%), 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%). Two sky maps are available at this time and can be retrieved from the GraceDB event page: * "bayestar.fits.gz,0", a preliminary localization generated by BAYESTAR [4] for an earlier trigger, not the current preferred event, and * "bayestar.fits.gz,1", an initial localization generated by BAYESTAR [4]. For the bayestar.fits.gz,1 sky map, the 90% credible region is 1297 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1168 +/- 330 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] Nitz et al. PRD 98, 024050 (2018) [2] Qi Chu, PhD Thesis, The University of Western Australia (2017) [3] Messick et al. PRD 95, 042001 (2017) [4] Singer & Price PRD 93, 024013 (2016)