TITLE:   GCN CIRCULAR
NUMBER:  35509
SUBJECT: LIGO/Virgo/KAGRA S240109a: Updated Sky localization
DATE:    24/01/09 15:18:48 GMT
FROM:    Colm Talbot at University of Chicago <talbotcolm@gmail.com>

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

We have conducted further analysis of the LIGO Hanford Observatory (H1) data around the time of the compact binary merger (CBC) candidate S240109a (GCN Circular 35502). 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/S240109a

For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 28048 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1594 +/- 567 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/userguide/.

 [1] Ashton et al. ApJS 241, 27 (2019) and Morisaki et al. arXiv:2307.13380 (2023)