TITLE:   GCN CIRCULAR
NUMBER:  21661
SUBJECT: LIGO/Virgo G298936: Updated localization from gravitational-wave data 
DATE:    17/08/23 17:03:29 GMT
FROM:    Leo Singer at NASA/GSFC  <leo.p.singer@nasa.gov>

The LIGO Scientific Collaboration and the Virgo Collaboration report:

In GCN 21656, we reported the identification of the binary black hole
candidate G298936 in data from LIGO Hanford Observatory (H1) and LIGO
Livingston Observatory (L1). We have obtained and inspected the Virgo (V1)
data at the time of the candidate and found them to be suitable for manual
re-analysis using the PyCBC pipeline.

An updated BAYESTAR localization using data from all three detectors (H1,
L1, V1) is now available for retrieval from the GraceDB page:
bayestar-HLV.fits.gz. This is the preferred sky map at this time.

Compared to the initial BAYESTAR localization, the 50% area has decreased
from 605 to 277 deg2 and the 90% area has decreased from 2145 to 1219
deg2. The all-sky, marginalized luminosity distance estimate is 1541 +/-
415 Mpc (a posteriori mean +/- standard deviation), largely consistent
with the original estimate.

We will continue to refine the sky map using offline parameter estimation.