{
  "bibcode": "2020GCN.26640....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe identified the compact binary merger candidate S200105ae in data\nfrom LIGO Livingston Observatory (L1) and Virgo Observatory (V1) at\n2020-01-05 16:24:26.057 UTC (GPS time: 1262276684.057). The candidate\nwas found by the GstLAL [1] analysis pipeline. LIGO Hanford\nObservatory (H1) was offline at the time.\n\nThe signal-to-noise ratio (SNR) was below threshold in V1 so the\ncandidate was treated as a single-instrument event. The false alarm\nrate (FAR) estimated from the L1 trigger, 7.6e-07 Hz -- or about 24\nper year -- was above the threshold we normally use for issuing a\npublic alert.  However, after further offline analysis of the\ncandidate, we believe that its significance is greater than that\ncalculated in real-time processing.  Follow-up observations may\ntherefore be justified.\n\nThe event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S200105ae\n\nWe cannot quantify the probability of this event being astrophysical\nat this time.  However, if it is astrophysical, it is most consistent\nwith being a neutron star - black hole (NSBH) event.  Under this\nassumption, there is strong evidence for the lighter compact object\nhaving a mass < 3 solar masses (HasNS: >99%).  Using the masses\nand spins inferred from the signal, it is possible but unlikely that the\nmerger left matter outside the final compact object.  (HasRemnant was\nestimated as 12% by the initial analysis, but this value is considered\nuncertain.)\n\nOne sky map is available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.fits.gz,0, an initial localization generated by BAYESTAR [2].\nNo GCN notice has been issued for this candidate.\n\nFor the bayestar.fits.gz sky map, the 90% credible region is 7719\ndeg2, dominated by the L1 antenna response. Marginalized over the\nwhole sky, the a posteriori luminosity distance estimate is 265 +/- 71\nMpc (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\n<https://emfollow.docs.ligo.org/userguide/>.\n\n [1] Messick et al. PRD 95, 042001 (2017)\n [2] Singer & Price PRD 93, 024013 (2016)",
  "circularId": 26640,
  "createdOn": 1578335126000,
  "email": "pshawhan@umd.edu",
  "subject": "LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate",
  "submitter": "Peter Shawhan at U of Maryland/LSC  <pshawhan@umd.edu>",
  "eventId": "LIGO/Virgo S200105ae"
}