TITLE:   GCN CIRCULAR
NUMBER:  35305
SUBJECT: LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
DATE:    23/12/07 16:36:13 GMT
FROM:    Sylvia Biscoveanu at MIT <sylvia.biscoveanu@ligo.org>

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 S231206ca (GCN Circular 35297). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits, distributed via GCN Notice, is available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/superevents/S231206ca

For the Bilby.multiorder.fits sky map, the 90% credible region is 2335 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3230 +/- 1141 Mpc (a posteriori mean +/- standard deviation).

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 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/userguide/.

[1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023)
[2] Rose et al. arXiv:2201.05263 (2022) and Pankow et al. PRD 92, 023002 (2015)