GCN Circular 21056
The LIGO Scientific Collaboration and Virgo Collaboration report: We have completed a Bayesian parameter-estimation analysis of the GW candidate G268556 (GCN 20364) under the assumption that the signal arises from a compact binary coalescence (CBC) and using the latest calibration of the GW strain data. The data are still found to be consistent with a binary black hole merger. A refined sky localization is now available and can be retrieved from GraceDB (https://gracedb.ligo.org/events/G268556): * LALInference_f.fits.gz, produced using a coherent Bayesian analysis (Veitch et al. PRD 91, 042003) of the full GW signal including spin precession, and incorporating the potential effects of calibration errors. We regard this LALInference sky map as the most authoritative localization for this event. The localization is similar in structure to previous ones (GCN 20364 and 20385), with two arcs tracing part of the annulus set by the 3 ms delay in arrival time between the Hanford and Livingston observatories. The differences compared to previous localizations are primarily a consequence of the improved calibration of the data.