RX J1131-1231
LENSED · SCHWARZSCHILD FROM ACCRETION QUASAR · INCLINATION NOT MEASURED
OVERVIEW
] BLACK HOLERX J1131-1231 is a in the constellation Crater, 12.71 from Earth. It was discovered in 2003.
A lensed quasar whose X-ray spectrum gave the first spin measurement for a black hole this far away: it turns at about half the speed of light. Spin is a record of how the hole was fed, so measuring it anywhere but nearby is a statement about the history of the whole population.
- WHAT IT IS
- Quasar
- HOW FAR
- 12.71
A luminosity distance, from its redshift — how faint it looks. The light itself left 6.00 billion years ago.
OBSERVING
] FROM WHERE YOU AREWhat it takes to see RX J1131-1231 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 RX J1131-1231 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
- 21.8
- PROPER MOTION SINCE
- none published
Computed for 2026-09-03 00:00 UT. No proper motion is published for RX J1131-1231, 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
] 2 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 KIND OF THING IT IS
What the object is in itself, rather than how it happens to look from here.
- Accretion state
- quasar — a thin disc near its Eddington limit
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.
- Redshift (z)
ALSO KNOWN AS
] 1 DESIGNATIONS- Common name RX J1131-1231
LOOK IT UP ELSEWHERE
] 1 SERVICEEach 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.
- VizieR5″ around 172.9647 -12.5330
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. RX J1131-1231 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/rx-j1131-1231
@misc{spacecatalog_rx-j1131-1231,
author = {{SpaceCatalog}},
title = {{RX J1131-1231}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/rx-j1131-1231},
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.