TITLE: GCN CIRCULAR NUMBER: 34816 SUBJECT: LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate DATE: 23/10/14 05:00:50 GMT FROM: P. Prasia at Inter-University Centre for Astronomy and Astrophysics <prasia.p@ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S231014r during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-10-14 04:05:32.990 UTC (GPS time: 1381291550.990). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], and PyCBC Live [4] analysis pipelines. S231014r is an event of interest because its false alarm rate, as estimated by the online analysis, is 1e-08 Hz, or about one in 3 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S231014r The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassgap) is <1%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 29 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1807 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2857 +/- 903 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Klimenko et al. PRD 93, 042004 (2016) [2] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al. arXiv:2305.05625 (2023) [3] Aubin et al. CQG 38, 095004 (2021) [4] Dal Canton et al. ApJ 923, 254 (2021) [5] Chatterjee et al. ApJ 896, 54 (2020) [6] Singer & Price PRD 93, 024013 (2016) View this GCN Circular online at https://gcn.nasa.gov/circulars/34816. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...