OVERVIEW
] BLACK HOLESagittarius A* is a supermassive black hole in the constellation Sagittarius, 26 673 from Earth. Its mass is 4.15×10⁶ . It is catalogued as Sgr A*. It was discovered in 1974.
The supermassive black hole at the center of the Milky Way. For decades it was known only by the frantic orbits of nearby stars; in 2022 the Event Horizon Telescope resolved its glowing ring directly. Everything in our galaxy — including you — orbits this point.
- WHAT IT IS
- Supermassive black hole
- HOW FAR
- 26 673
The light arriving now left it that long ago.
THE MODEL
] LENSEDCALCULATED · NOT AN OBSERVATION · SCHWARZSCHILD RADIUS FROM THE MASS · 4 150 000 M☉ · ACCRETION HOT FLOW · INCLINATION 30°
The black disc is the shadow, 2.6 times wider than the horizon that casts it, and every ray in the frame is a null geodesic of the Schwarzschild metric. Too little gas is falling in for it to cool and settle into a disc, so what is drawn is a thin, hot, transparent flow — brightest where light loops the hole and passes through it twice. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, drawn from where the camera actually is — but every one of them is within 170 parsecs of the Sun and this object is much further out, so what is in the frame is that whole neighbourhood seen from outside it, piled into a knot around the Sun. The rest of the sky from here is not something this catalogue knows.
IMAGES
] 1 FRAMES- EHT Collaboration
CC BY 4.0
OBSERVING
] FROM WHERE YOU AREWhat it takes to see Sagittarius A* for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when Sagittarius A* is worth going out for.
APPARENT PLACE
] EQUINOX J2026.7Where a telescope has to be pointed today, which is not quite where the catalogue records the object: the coordinate grid itself has turned since the year 2000 the catalogue is referred to.
- RIGHT ASCENSION
- DECLINATION
- GRID TURNED SINCE
- 22.4
- PROPER MOTION SINCE
- none published
Computed for 2026-08-27 00:00 UT. No proper motion is published for Sagittarius A*, so nothing here moves the object; what separates this from the catalogued position above is the coordinate grid turning under it — about fifty arcseconds a year of precession since 2000, and the small nodding of the Earth’s axis on top of that. Aberration and refraction are not included, and neither is parallax; each is under an arcminute, which is also about as well as the catalogued position is known. The same figure for any date.
CATALOG DATA
] 3 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT IT IS MADE OF
What the object is in itself, rather than how it happens to look from here.
- Accretion state
- hot flow — too little gas to cool, so not a disc at all
- Mass
- 4 150 000
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- Accretion plane inclination
- 30
ALSO KNOWN AS
] 2 DESIGNATIONS- Common name Sagittarius A*
- Common name Sgr A*
LOOK IT UP ELSEWHERE
] 3 SERVICESEach link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.
- SIMBADSgr A*
Cross-identifications, measured values and the reference behind each of them.
- ADSobject:"Sgr A*"
Papers indexed against this object rather than against the string, newest first.
- VizieR5″ around 266.4168 -29.0078
Every published table with a row at this position, searched by coordinates rather than by name.
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Sagittarius A* [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/sgr-a
@misc{spacecatalog_sgr-a,
author = {{SpaceCatalog}},
title = {{Sagittarius A*}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/sgr-a},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from SpaceCatalog curated data.}
}The values above were taken from SpaceCatalog curated data — CC-BY-4.0. Citing this page does not replace citing that catalogue.
RECENT ACTIVITY
] 6 ITEMS- Time-Lapse of the Star S301 Orbiting the Black Hole in the Center of the Galaxy2026-08-21 · NASA APOD · IMAGE
- A deep learning algorithm for black hole spin estimation using hot-spot secondary images2026-08-18 · arXiv · PAPER · Aristomenis I. Yfantis, Rami Al-Belmpeisi
- The Spin Angular Momentum and Black Hole Mass Components of Sagittarius A*2026-08-18 · arXiv · PAPER · Ruth A. Daly
- The Spin Angular Momentum and Black Hole Mass Components of Sagittarius A*2026-08-18 · arXiv · PAPER · Ruth A. Daly
- Webb reveals dust and water surviving in the extreme environment around the Milky Way’s central black hole2026-08-11 · ESA/Webb · RELEASE
- Dust and water spotted close to giant black hole2026-08-11 · ESA · RELEASE
NASA APOD · arXiv · ESA/Webb · ESA · UPDATED DAILY