{
  "bibcode": "2017GCN.21221....1L",
  "body": "The LIGO Scientific Collaboration and Virgo Collaboration report:\n\nThe PyCBC binary-merger search (Nitz et al., arXiv:1705.01513; Usman\net al. 2016, CQG 33, 215004) identified candidate G288732 in analysis\nof data from the LIGO Livingston Observatory (L1) at 2017-06-08\n02:01:16.492 UTC (GPS time: 1180922494.492). This circular was delayed\nas the LIGO Hanford detector was not in observing mode at this time\nand manual investigations were required.\n\nThe Livingston detector was operating nominally at the time of the\ntrigger, however the Hanford detector was undergoing a period of\nactive commissioning at the time of the trigger. The trigger was first\nidentified by inspection of PyCBC triggers from the Livingston\ndata. Manual follow-up of the Hanford data identified a coincident\ntrigger with consistent parameters.  The Virgo detector was locked but\nin a commissioning mode at the time; Virgo data has not yet been used\nin this analysis. Offline analysis is ongoing.\n\nCommissioning activities were ongoing for two minutes around the time\nof the trigger, but studies suggest this activity only affected\nfrequencies below 30 Hz. This is below the starting frequency of the\nmanual re-analysis. Other than the Hanford activity below 30 Hz, the\nstate and calibration of the detectors appears nominal.\n\nDue to the Hanford commissioning activities, the amount of data\navailable to estimate the noise background was limited to\napproximately 15 minutes. Using these data, we estimate that the false\nalarm rate of G288732 is less than (i.e. more significant than) 2.6\nper year, however the signal-to-noise ratio of this candidate is\nconsistent with a higher significance.\n\nThe event's properties can be found at this URL:\nhttps://gracedb.ligo.org/events/G288732\n\nIf G288732 is astrophysical, it is likely to be a binary black hole\nmerger.\n\nThe gstlal binary-merger search (Messick et al., 2016, PRD 95, 042001)\nidentified a consistent trigger in the Livingston data at the time of\nthe candidate.\n\nOne sky map with distance information (e.g., Singer et al. 2016, ApJL 829,\n15) is available at this time and can be retrieved from the GraceDB event\npage: bayestar.fits.gz, an initial localization generated by the BAYESTAR\npipeline. The 50% credible region spans about 230 deg2 and the 90% region\nabout 860 deg2. The luminosity distance is 320 +/- 100 Mpc (all-sky mean\n+/- standard deviation). This is the preferred sky map at this time.\n\nWe caution that the parameters of this candidate may be subject to change\nas data-quality and calibration studies are ongoing.",
  "circularId": 21221,
  "createdOn": 1496935766000,
  "email": "becsybence@caesar.elte.hu",
  "subject": "LIGO/Virgo G288732: Identification of a GW Binary Merger Candidate",
  "submitter": "Bence Becsy at Eotvos U  <becsybence@caesar.elte.hu>",
  "eventId": "LIGO/Virgo G288732"
}