{
  "createdOn": 1692467728297,
  "circularId": 34494,
  "subject": "LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate",
  "eventId": "LIGO/Virgo/KAGRA S230819ax",
  "bibcode": "2023GCN.34494....1L",
  "submittedHow": "web",
  "submitter": "sushant.sharma-chaudhary@ligo.org",
  "body": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the\nKAGRA Collaboration report:\n\nWe identified the compact binary merger candidate S230819ax during\nreal-time processing of data from LIGO Hanford Observatory (H1) and\nLIGO Livingston Observatory (L1) at 2023-08-19 17:19:10.455 UTC (GPS\ntime: 1376500768.455). The candidate was found by the CWB [1], GstLAL\n[2], MBTA [3], oLIB [4], and SPIIR [5] analysis pipelines.\n\nS230819ax is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 8.8e-09 Hz, or about one in 3\nyears. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S230819ax\n\nThe classification of the GW signal, in order of descending\nprobability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS\n(<1%).\n\nThere were noise transients at the LIGO Hanford and evidence for \nnonstationary noise at both LIGO detectors which may affect the \nparameters or the significance of the candidate.\n\nAssuming the candidate is astrophysical in origin, the probability\nthat the lighter compact object is consistent with a neutron star mass\n(HasNS) is <1%. [6] Using the masses and spins inferred from the\nsignal, the probability of matter outside the final compact object\n(HasRemnant) is <1%. [6] Both HasNS and HasRemnant consider the\nsupport of several neutron star equations of state. The probability\nthat either of the binary components lies between 3 and 5 solar masses\n(HasMassgap) is <1%.\n\nTwo sky maps are available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.multiorder.fits,1, an initial localization generated by\nBAYESTAR [7], distributed via GCN notice about 25 seconds after the\ncandidate event time.\n * bayestar.multiorder.fits,2, an initial localization generated by\nBAYESTAR [7], distributed via GCN notice about 5 minutes after the\ncandidate event time.\n\nThe preferred sky map at this time is bayestar.multiorder.fits,2. For\nthe bayestar.multiorder.fits,2 sky map, the 90% credible region is\n4126 deg2. Marginalized over the whole sky, the a posteriori\nluminosity distance estimate is 4872 +/- 1527 Mpc (a posteriori mean\n+/- standard deviation).\n\nFor further information about analysis methodology and the contents of\nthis alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide\nhttps://emfollow.docs.ligo.org/userguide/.\n\n [1] Klimenko et al. PRD 93, 042004 (2016)\n [2] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al.\narXiv:2305.05625 (2023)\n [3] Aubin et al. CQG 38, 095004 (2021)\n [4] Lynch et al. PRD 95, 104046 (2017)\n [5] Chu et al. PRD 105, 024023 (2022)\n [6] Chatterjee et al. ApJ 896, 54 (2020)\n [7] Singer & Price PRD 93, 024013 (2016)\n"
}