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GCN Circular 35481

Subject
LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
Date
2024-01-05T01:00:31Z (3 months ago)
From
Soichiro Morisaki at U. of Tokyo <soichiro.morisaki@ligo.org>
Via
Web form
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 S240104bl (GCN Circular 35480). 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/S240104bl

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 27949 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1978 +/- 618 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)
[2] Rose et al. arXiv:2201.05263 (2022) and Pankow et al. PRD 92, 023002 (2015)
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