//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19341 SUBJECT: LIGO/Virgo G197392 / LVT151012: Identification of a GW CBC Candidate DATE: 16/04/25 15:42:45 GMT FROM: Leo Singer at NASA/GSFC The LIGO Scientific Collaboration and Virgo report: The offline gstlal and pycbc CBC analyses identified candidate G197392, also known as LVT (LIGO/Virgo Trigger) 151012, during offline processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2015-10-12 09:54:43.444 UTC (GPS time: 1128678900.444). The candidate's false alarm rate was reported as 1 per 2.3 years and a corresponding false alarm probability of 0.02 (2.1 sigma) in LSC+Virgo 2016a (http://adsabs.harvard.edu/abs/2016PhRvL.116f1102A) and LSC+Virgo 2016b (http://adsabs.harvard.edu/abs/2016arXiv160203839T). There is an 80--90% chance that the signal has an astrophysical origin. If it does, then the source is a binary black hole merger. LVT151012 was not recovered in real time because the template banks for the low-latency CBC searches were not configured at the time to include BBHs, and the signal was too weak to be detected by the un-modeled burst searches. The offline significance estimate makes it an event of interest because it passes our stated alert threshold of ~1/month. The event's properties can be found at this URL: https://gracedb.ligo.org/events/G197392 The available sky map, LALInference_skymap.fits.gz, was generated using Bayesian Markov-chain Monte Carlo and nested sampling to perform forward modeling of the full GW signal including the inspiral and merger as well as the effects of calibration uncertainty. The localization is mainly determined by the 0.6-ms time delay on arrival of the signal between H1 and L1. It favors two long islands on opposite sides of a roughly 2 deg wide annulus. The 90% credible region spans an area of about 1700 deg2. We regard this sky map as the most accurate to date for this event. The BAYESTAR localization derived from triangulation of times, amplitudes, and phases on arrival is qualitatively and quantitatively consistent with the LALInference sky map. The localizations produced by the cWB and LIB un-modeled burst analyses are significantly coarser due to the low signal-to-noise ratio, but they are qualitatively consistent with the CBC localizations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19541 SUBJECT: LIGO/Virgo G197392 / LVT151012: Sky maps and other data available in LOSC DATE: 16/06/16 22:16:24 GMT FROM: Peter Shawhan at U of Maryland/LSC The LIGO Scientific Collaboration and Virgo report: A data release for the gravitational-wave candidate event LVT151012 (originally named G197392) is available for public use from the LIGO Open Science Center (LOSC) at https://losc.ligo.org/events/LVT151012 . This includes: * Numerical values of estimated source parameters * 4096 s of gravitational-wave strain data around the time of LVT151012 * Sky localization FITS files, including the final LALInference sky map * Skymap Viewer links to visualize the sky maps * Links to tutorials and other information about LVT151012