{
  "subject": "LIGO/Virgo S190521g: Identification of a GW compact binary merger candidate",
  "eventId": "LIGO/Virgo S190521g",
  "bibcode": "2019GCN.24621....1L",
  "createdOn": 1558412391000,
  "circularId": 24621,
  "submitter": "Geoffrey Mo at LIGO  <geoffrey.mo@ligo.org>",
  "email": "geoffrey.mo@ligo.org",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe identified the compact binary merger candidate S190521g during\nreal-time processing of data from LIGO Hanford Observatory (H1), LIGO\nLivingston Observatory (L1), and Virgo Observatory (V1) at 2019-05-21\n03:02:29.447 UTC (GPS time: 1242442967.447). The candidate was found\nby the PyCBC Live [1], CWB [2], GstLAL [3], and SPIIR [4] analysis\npipelines.\n\nS190521g is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 3.8e-09 Hz, or about one in 8\nyears. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S190521g\n\nThe classification of the GW signal, in order of descending\nprobability, is BBH (97%), Terrestrial (3%), BNS (<1%), NSBH (<1%),\nor MassGap (<1%).\n\nAssuming the candidate is astrophysical in origin, there is strong\nevidence against the lighter compact object having a mass < 3 solar\nmasses (HasNS: <1%). Using the masses and spins inferred from the\nsignal, there is strong evidence against matter outside the final\ncompact object (HasRemnant: <1%).\n\nOne sky map is available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.fits.gz, an updated localization generated by\n   BAYESTAR [5], distributed via GCN notice about 6 minutes after\n   the candidate\n\nFor the bayestar.fits.gz sky map, the 90% credible region is 1163 deg2.\nMarginalized over the whole sky, the a posteriori luminosity distance\nestimate is 663 +/- 156 Mpc (a posteriori mean +/- standard\ndeviation).\n\nWe have reason to believe that the distance may be underestimated\nbecause different search pipelines have reported a range of distances.\nThe two-dimensional sky map (right ascension and declination)\nis in good agreement across pipelines. Offline analyses to resolve\nthis issue are ongoing.\n\nFor further information about analysis methodology and the contents of\nthis alert, refer to the LIGO/Virgo Public Alerts User Guide\n<https://emfollow.docs.ligo.org/userguide/>.\n\n [1] Nitz et al. PRD 98, 024050 (2018)\n [2] Klimenko et al. PRD 93, 042004 (2016)\n [3] Messick et al. PRD 95, 042001 (2017)\n [4] Qi Chu, PhD Thesis, The University of Western Australia (2017)\n [5] Singer & Price PRD 93, 024013 (2016)"
}