{
  "bibcode": "2020GCN.27965....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\n*** This is a test of the Early Warning alert system resulting from archival\nO3 data. Times and sky localizations are fictitious. ***\n\nWe identified the compact binary merger candidate MS200615ce during\nreal-time processing of data from LIGO Hanford Observatory (H1) and\nVirgo Observatory (V1) at 2020-06-15 14:33:36.473 UTC (GPS time:\n1276266834.473). The candidate was found by the GstLAL [1], PyCBC Live\n[2], and MBTAOnline [3] analysis pipelines.\n\nMS200615ce is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 9e-19 Hz, or about one in 1e11\nyears. The event's properties can be found at this URL:\nhttps://gracedb.ligo.org/superevents/MS200615ce\n\nThe classification of the GW signal, in order of descending\nprobability, is MassGap (>99%), Terrestrial (<1%), BNS (<1%), BBH\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\n19%. Using the masses and spins inferred from the signal, the\nprobability of matter outside the final compact object (HasRemnant) is\n<1%.\n\nTwo sky maps are available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.fits.gz,0, an initial localization generated by BAYESTAR [4],\ndistributed via GCN notice about 52 seconds after the candidate event time.\n * bayestar.fits.gz,1, an initial localization generated by BAYESTAR [4],\ndistributed via GCN notice about 5 minutes after the candidate event time.\n\nThe preferred sky map at this time is bayestar.fits.gz,1. For the\nbayestar.fits.gz,1 sky map, the 90% credible region is 354 deg2.\nMarginalized over the whole sky, the a posteriori luminosity distance\nestimate is 330 +/- 79 Mpc (a posteriori mean +/- standard deviation).\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] Nitz et al. PRD 98, 024050 (2018)\n [3] Adams et al. CQG 33, 175012 (2016)\n [4] Singer & Price PRD 93, 024013 (2016)\n [5] Singer & Price PRD 93, 024013 (2016)\n [6] Chatterjee et al. The Astrophysical Journal 896, 1 (2020)",
  "circularId": 27965,
  "createdOn": 1592312825000,
  "email": "surabhi.sachdev@gmail.com",
  "subject": "LIGO/Virgo MS200615ce: Identification of a test binary black hole candidate",
  "submitter": "Surabhi Sachdev at LVC  <surabhi.sachdev@gmail.com>"
}