{
  "bibcode": "2019GCN.24168....1L",
  "body": "The LIGO Scientific Collaboration and the Virgo Collaboration report:\n\nWe identified the compact binary merger candidate S190425z during\nreal-time processing of data from LIGO Livingston Observatory (L1) and\nVirgo Observatory (V1) at 2019-04-25 08:18:05.017 UTC (GPS time:\n1240215503.017). The candidate was found by the GstLAL [1] and PyCBC\nLive [2] analysis pipelines.\n\nThe signal-to-noise ratio (SNR) was below threshold in V1 so the\ncandidate was treated as a single-instrument event and no automated\npreliminary notice was sent. Nonetheless, the V1 SNR is consistent\nwith the L1 data given the relative sensitivities of the detectors.\nLIGO Hanford Observatory (H1) was offline at the time.\n\nS190425z is an event of interest because its false alarm rate as\nestimated by the online analysis is 4.5e-13 Hz, or about one in 7e4\nyears. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S190425z\n\nThe classification of the GW signal, in order of descending\nprobability, is BNS (>99%), Terrestrial (<1%), NSBH (<1%), BBH (<1%),\nor MassGap (<1%).\n\nAssuming the candidate is astrophysical in origin, there is strong\nevidence for the lighter compact object having a mass < 3 solar masses\n(HasNS: >99%). Using the masses and spins inferred from the signal,\nthere is strong evidence for matter outside the final compact object\n(HasRemnant: >99%).\n\nOne skymap is available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.fits.gz, an initial localization generated by BAYESTAR [3],\n   distributed via GCN notice about 42 minutes after the candidate.\n\nFor the bayestar.fits.gz skymap, the 90% credible region is 10183\ndeg2. Marginalized over the whole sky, the a posteriori luminosity\ndistance estimate is 155 +/- 45 Mpc (a posteriori mean +/- standard\ndeviation). The skymap is coarser than usual due to the low\nsignal-to-noise ratio in V1; the localization is dominated by the L1\nantenna pattern.\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] Singer & Price PRD 93, 024013 (2016)",
  "circularId": 24168,
  "createdOn": 1556185993000,
  "email": "leo.p.singer@nasa.gov",
  "subject": "LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate",
  "submitter": "Leo Singer at GSFC  <leo.p.singer@nasa.gov>",
  "eventId": "LIGO/Virgo S190425z"
}