{
  "bibcode": "2017GCN.21513....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe performed a preliminary offline analysis using the PyCBC search (Nitz\net al. arxiv:1705.01513, 2017) of the binary neutron star candidate\nG298048 (LSC and Virgo, GCN 21505, 21509, 21510) identified in low-latency\nby the gstlal online search (Messick et al. Phys. Rev. D 95, 042001, 2017).\n\nA trigger consistent with a binary neutron star merger is observed at GPS\ntime 1187008882.443 (2017-08-17 12:41:04 UTC) in both the LIGO Livingston\n(L1) and LIGO Hanford (H1) detectors. The trigger is below threshold in\nVirgo because of the antenna pattern for Virgo (V1) at the time and\nlocation of this event, but the Virgo instrument contributes to the\nlocalization. The duration of the gravitational-wave signal is\napproximately 74 seconds from the search���s low-frequency cutoff of 27 Hz\nto the binary merger.\n\nInvestigation of L1 data identified a noise transient from a known class\nof instrumental glitches during the inspiral signal. The duration of this\nglitch is a small fraction of a second and does not appear to affect the\nsignal at times away from the glitch. To make an improved preliminary\nestimate of the sky position, we re-analyzed the data, removing the L1\nnoise transient at GPS time 1187008881.389 by multiplying the strain data\nwith a Tukey window, such that the total duration of the zeroed data is\n0.2 s and the total duration of the Tukey window is 1.2 s.\n\nAn updated BAYESTAR sky map (Singer et al. 2016, ApJL 829, 15) that uses\ndata from all three gravitational-wave observatories (H1, L1, and V1) is\navailable for retrieval from the GraceDB page\n(https://gracedb.ligo.org/events/view/G298048): bayestar-HLV.fits.gz. The\ncentroid (maximum a posteriori) sky location is R.A.=12h57m, Dec.=-17d51m.\nThe 50% credible region spans about 9 deg2 and the 90% region about 31\ndeg2. The luminosity distance is 40 +/- 8 Mpc (all-sky a posteriori mean\n+/- standard deviation). This is the preferred sky map at this time.\n\nIf we assume that the binary is either face on or face off in the plane of\nthe sky, then we obtain a revised estimate of luminosity distance of 50\n+/- 3 Mpc. This assumption does not significantly affect the overall 2D\nlocalization projected onto the sky, but reduces the 3D volume of the\nlocalization (e.g. Pankow et al. 2017, ApJ 834, 154).\n\nWe caution that the parameters and significance of this candidate may be\nsubject to change as data-quality, calibration, and full parameter\nestimation studies are ongoing.",
  "circularId": 21513,
  "createdOn": 1502992491000,
  "email": "leo.p.singer@nasa.gov",
  "subject": "LIGO/Virgo G298048: Further analysis of a binary neutron star candidate with updated sky localization",
  "submitter": "Leo Singer at NASA/GSFC  <leo.p.singer@nasa.gov>",
  "eventId": "LIGO/Virgo G298048"
}