TITLE: GCN CIRCULAR NUMBER: 41795 SUBJECT: LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification DATE: 25/09/11 13:17:25 GMT FROM: natalie.williams@uni-potsdam.de The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S250911ac (GCN Circular 41786). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline0.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250911ac %}Assuming the candidate is astrophysical, the updated classification of the GW signal, in order of descending probability, is BBH (96%), Terrestrial (4%), BNS (<1%), or NSBH (<1%). For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 952 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1124 +/- 285 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41795. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...