GCN Circular 38144

The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:

We have conducted further analysis of the LIGO Livingston Observatory (L1) and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S241109p (GCN Circular 38138
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). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/superevents/S241109p

After parameter estimation by RapidPE-RIFT [2], the updated classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).

For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 1761 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2282 +/- 1082 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
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 and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040
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 [2] Rose et al. (2022) arXiv:2201.05263
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 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002
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