{
  "bibcode": "2019GCN.26334....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe identified the compact binary merger candidate S191204r during\nreal-time processing of data from LIGO Hanford Observatory (H1), LIGO\nLivingston Observatory (L1), and Virgo Observatory (V1) at 2019-12-04\n17:15:26.092 UTC (GPS time: 1259514944.092). The candidate was found\nby the GstLAL [1], CWB [2], MBTAOnline [3], and SPIIR [4] analysis\npipelines.\n\nS191204r is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 3.1e-25 Hz, or about one in 1e17\nyears. The event's properties can be found at this URL:\nhttps://gracedb.ligo.org/superevents/S191204r\n\nAt the time of the event the Virgo detector was performing calibration\ninjections, and was in low noise mode but not observing. At the exact\ntime of the event Virgo was between calibration injections and the\ndata was undisturbed. After discussion we agreed that the data was\nusable for sky localization.\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, the probability\nthat the lighter compact object has a mass < 3 solar masses (HasNS) is\n<1%. Using the masses and spins inferred from the signal, the\nprobability of matter outside the final compact object (HasRemnant) is\n<1%.\n\nThree sky maps are available at this time and can be retrieved from\nthe GraceDB event page:\n * bayestar.fits.gz,0, an initial localization generated by BAYESTAR\n[5], distributed via GCN notice about 42 minutes after the candidate\nevent time.\n * bayestar.fits.gz,1, an initial localization generated by BAYESTAR\n[5], distributed via GCN notice about 54 minutes after the candidate\nevent time.\n * bayestar.fits.gz,2, an initial localization generated by BAYESTAR\n[5], distributed via GCN notice about an hour after the candidate\nevent time.\n\nThe preferred sky map at this time is bayestar.fits.gz,2. For the\nbayestar.fits.gz,2 sky map, the 90% credible region is 103 deg2.\nMarginalized over the whole sky, the a posteriori luminosity distance\nestimate is 678 +/- 149 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] Klimenko et al. PRD 93, 042004 (2016)\n [3] Adams et al. CQG 33, 175012 (2016)\n [4] Qi Chu, PhD Thesis, The University of Western Australia (2017)\n [5] Singer & Price PRD 93, 024013 (2016)\n\n[GCN OPS NOTE (04dec19):  The typo extra \"SUBJECT:\" was removed from the SUBJECT:-line.]",
  "circularId": 26334,
  "createdOn": 1575484907000,
  "email": "deep@uwm.edu",
  "subject": "LIGO/Virgo S191204r: Identification of a GW compact binary merger candidate",
  "submitter": "Deep Chatterjee at University of Wisconsin, Milwaukee  <deep@uwm.edu>",
  "eventId": "LIGO/Virgo S191204r"
}