GCN Circular 41702
Subject
LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
Date
2025-09-04T16:44:30Z (5 days ago)
From
Michael J. Williams at University of Portsmouth <michael.williams@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), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250904ae (GCN Circular 41689). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S250904ae
For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 931 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3545 +/- 913 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