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GS 2023+338 | Black Holes | Apex Andromeda | Apex Andromeda

Black Holes/GS 2023+338

ConfirmedStellar-Mass Binary

Unified black-hole record

GS 2023+338

Dynamically confirmed black hole

Also known as V404 Cyg

Mass9 M☉

Distance7.795K ly

HostNot reported by source catalogs

Drag to orbitScroll to zoomEmbedded animation playing

3D model “Blackhole” by rubykamen, licensed under CC BY 4.0.

Catalog record

Identity and classification

ID: vizier-blackcat:J/ApJS/222/15/table12:75
Canonical name: GS 2023+338
Alternate names: V404 Cyg
Black-hole type: Stellar-Mass Binary
Status: Confirmed
Population: Catalog
Confidence: Dynamically confirmed black hole
Host galaxy: Not reported by source catalogs

Position

Coordinates and distance

Right ascension (RA): 306.01591667°
Declination (Dec): 33.86719444°
Galactic longitude (l): 73.1188°
Galactic latitude (b): -2.0914°
Distance: 7.795K light-years
Distance error: 456.619 light-years
Redshift: Not reported by source catalogs

Physical profile

Mass, spin, and system

Mass: 9 solar masses
Mass error, lower: 0.6 solar masses
Mass error, upper: 0.2 solar masses
Spin: Not reported by source catalogs
Companion: V404 Cyg
Companion type: K3III
Orbital period: 6.471291666666667 days
Inclination: 52°

Evidence

Detection and discovery

Detection method: Dynamical mass measurement in an X-ray binary
Discovery year: 1989
Discovery observatory: GS
X-ray properties: WATCHDOG source type: BH,T,R,J?,W
Radio properties: Not reported by source catalogs
Gravitational-wave event: Not reported by source catalogs

Provenance

Sources and refresh state

Source catalog: VizieR J/ApJS/222/15 (WATCHDOG/BlackCAT)
Source reference: 2016ApJS..222...15T
Last updated: 2026-08-31T01:34:41.049Z
Source record: Open provider record ↗

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