2026-09-05 15:48:26 UTC
JD 2461289.16
STATION 04 · MULTI-MESSENGER WIRE DOSSIER Gravitational Wave CONFIRMED

GW230529_181500

“Merger in the Lower Mass Gap: Neutron Star Collides with Mystery Compact Object”
LIGO Livingston / KAGRA / Virgo (O4 Run) Trigger: 2023-05-29 18:15:00 UTC
ASTROPHYSICAL LOCALIZATION & TELEMETRY
FRAME: ICRS / J2000
Sky Coordinates 13h 09m 24.0s -24° 49' 12" (197.35000°, -24.82000°)
Cosmological Redshift z = 0.0450 Luminosity Dist: 650 Million ly (200 Mpc)
Constellation / Field Corvus / Hydra border Host Field Environment
Detection Significance Definitive Detection (FAR < 1 per 10,000 yr) Multi-detector confidence
chirp mass
1.81 M☉
primary mass
3.6 (+0.8 / -1.2) M☉ (Mass Gap Object)
secondary mass
1.4 (+0.6 / -0.2) M☉ (Neutron Star)
luminosity dist
200 (+100 / -100) Mpc
network snr
11.6 (LIGO Livingston single-detector confident)
sky area 90
25,200 deg²
merger type
NS-MassGap / NSBH

01 Scientific Overview & Source Physics

GW230529 represents a landmark gravitational wave detection by the LIGO-Virgo-KAGRA Collaboration during the O4 run. The primary component was determined to be 2.5 to 4.5 solar masses—placing it squarely in the elusive lower "mass gap" between known neutron stars and stellar-mass black holes. The secondary object was a 1.2 to 2.0 solar mass neutron star.

02 Multi-Messenger Follow-Up Campaign Matrix

Observatory / Instrument Spectral Regime Observational Detection & Counterpart Findings
ZTF / DECam
Optical
Rapid tiling of 90% sky map; no optical kilonova detected due to large error volume.
Fermi GBM
Gamma-ray
No contemporaneous sub-threshold gamma-ray burst identified within ±10s.
Swift XRT
X-ray
Target of Opportunity pointed at high-probability galaxy clusters.