{
  "bibcode": "2017GCN.21508....1B",
  "body": "I. Bartos, S. Countryman (Columbia), C. Finley (U Stockholm), E. Blaufuss (U Maryland), R. Corley, Z. Marka, S. Marka (Columbia) on behalf of the IceCube Collaboration\n\nThe analysis FOUND A COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATE detected by IceCube within the 500 second window surrounding G298048 within the BAYESTAR skymap. The coordinates of the reconstructed neutrino source are below:\n\n#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]\n------------------------------------------------------------------\n1.         -166.00       291.4        69.0        0.37         3.1\n\nWe searched IceCube online track-like neutrino candidates (GFU) detected in a [-500,500] second interval about the LIGO-Virgo trigger G298048. We compared the candidate source directions of 6 temporally-coincident neutrinos to the BAYESTAR skymap, with the following parameters:\n\n#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]\n------------------------------------------------------------------\n1.         -419.79       226.7        12.0        0.65         1.8\n2.         -266.61       239.6        19.6        1.04         1.6\n3.         -165.72       291.3        68.8        0.37         3.1\n4.         -153.47       182.0        -3.2        0.88         0.9\n5.          310.59         1.4        23.8        0.50         1.5\n6.          390.94       203.2         6.0        1.00         0.7\n\n\n(dt--time from GW in [seconds]; RA/Dec--sky location in [degrees]; E--reconstructed secondary muon energy in [TeV]; Sigma--uncertainty of direction reconstruction in [degrees])\n\nA coincident neutrino-GW skymap has been posted to GraceDB (<https://gracedb.ligo.org/apiweb/events/G298048/files/coinc_skymap_initial_icecube.png,0>). A JSON-formatted list of the above neutrinos can be downloaded from GraceDB at: <https://gracedb.ligo.org/apiweb/events/G298048/files/IceCubeNeutrinoList.json,0>\n\nIn addition, we are performing coincident searches with other IceCube data streams, including the high-energy starting events (HESE) and Supernova triggers.  HESE events have typical energies > 60 TeV and start inside the detector volume, leading to a relatively pure event sample with a high fraction of astrophysical neutrinos.  The SN trigger system is sensitive to sudden increases in photomultiplier counts across the detector, which could indicate a burst of MeV neutrinos.  We will submit separate GCN circulars if coincident HESE or SN triggers are found.\n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica.  For a description of the IceCube realtime alert system, please refer to <http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1610.01814>; for more information on joint neutrino and gravitational wave searches, please refer to <http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1602.05411>.",
  "circularId": 21508,
  "createdOn": 1502978711000,
  "email": "stefan.countryman@ligo.org",
  "subject": "LIGO/Virgo G298048: FOUND COINCIDENT IceCube neutrino observation",
  "submitter": "Stefan Countryman at LIGO Scientific Collaboration  <stefan.countryman@ligo.org>",
  "eventId": "LIGO/Virgo G298048"
}