{
  "bibcode": "2019GCN.25753....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe identified the compact binary merger candidate S190915ak during\nreal-time processing of data from LIGO Hanford Observatory (H1), LIGO\nLivingston Observatory (L1), and Virgo Observatory (V1) at 2019-09-15\n23:57:02.691 UTC (GPS time: 1252627040.691). The candidate was found\nby the GstLAL [1], SPIIR [2], CWB [3], and MBTAOnline [4] analysis\npipelines.\n\nS190915ak is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 9.7e-10 Hz, or about one in 32\nyears. The event's properties can be found at this URL:\nhttps://gracedb.ligo.org/superevents/S190915ak\n\nThe classification of the GW signal, in order of descending\nprobability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), MassGap\n(<1%), or NSBH (<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 BAYESTAR\n[5], distributed via GCN notice about 6 minutes after the candidate trigger time.\nFor the bayestar.fits.gz sky map, the 90% credible region is 528 deg2.\nMarginalized over the whole sky, the a posteriori luminosity distance\nestimate is 1557 +/- 381 Mpc (a posteriori mean +/- standard\ndeviation).\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] Messick et al. PRD 95, 042001 (2017)\n [2] Qi Chu, PhD Thesis, The University of Western Australia (2017)\n [3] Klimenko et al. PRD 93, 042004 (2016)\n [4] Adams et al. CQG 33, 175012 (2016)\n [5] Singer & Price PRD 93, 024013 (2016)\n\n[GCN OPS NOTE(15sep19): Per author's request, \"trigger time.\" was added\nto the end of the first sentence in the fifth paragraph.]",
  "circularId": 25753,
  "createdOn": 1568593669000,
  "email": "ajw@caltech.edu",
  "subject": "LIGO/Virgo S190915ak: Identification of a GW compact binary merger candidate",
  "submitter": "Alan Weinstein at Caltech/LIGO  <ajw@caltech.edu>",
  "eventId": "LIGO/Virgo S190915ak"
}