TITLE: GCN CIRCULAR NUMBER: 21284 SUBJECT: LIGO/Virgo G274296: Updated localization from LIGO data DATE: 17/06/29 20:29:07 GMT FROM: Marco Drago at Albert Einsein Inst/Hanover The LIGO Scientific Collaboration and Virgo report: We have performed the off-line analysis of the LIGO data around the time of the burst event G274296 using the Coherent WaveBurst (Klimenko et al., PRD 93, 042004 (2016)) with a better estimation of the background. The new estimated FAR is one event in 6 months. The low significance of this candidate is not expected to improve with further analysis. An updated localization, skyprobcc_cWB_170629.fits, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/events/G274296 This is the preferred sky map at this time. The localization is consistent with the previous sky map, however, its error region is smaller due to improved calculation of the coherent Waveburst skymaps for the low SNR events. The 50% credible region spans 245 deg2 and the 90% credible region spans 1153 deg2. Further updates on our analysis of this event will be sent as they become available. [GCN OPS NOTE(29jun17): Per adminstrator's request, the author-generated 5-line title block was removed, leaving only the GCN-generated 5-line title block.]