---
title: "The quasars"
url: "https://spacecatalog.org/black-holes/quasars"
release: "DR1"
licence: "Each object is under the terms of its own upstream catalogue, named on its page and in its markdown."
citation: null
---

# The quasars

The most distant quasar in this catalogue is [J0313-1806](https://spacecatalog.org/object/qso-j0313-1806), 244.8 Gly away. Next are ULAS J1342+0928 and ULAS J1120+0641.

A quasar is a supermassive black hole being fed hard enough that the gas falling towards it outshines every [star](https://spacecatalog.org/stars) in the [galaxy](https://spacecatalog.org/galaxies) around it. Ranked here by distance, furthest first, because that is the axis they were discovered along: the furthest are the youngest, and the ones at the top of this list were shining before most of the galaxies that exist had formed. The figures are luminosity distances — each redshift converted under the same cosmology as every galaxy here — which at these redshifts run several times larger than the light-travel figure a headline would quote.

## The top 39

| Name | Class | Mass | Distance | Mag | Constellation |
| --- | --- | --- | --- | --- | --- |
| [J0313-1806](https://spacecatalog.org/object/qso-j0313-1806) | Quasar | 1.6×10⁹ M☉ | 244.8 Gly | — | Eridanus |
| [ULAS J1342+0928](https://spacecatalog.org/object/ulas-j1342-0928) | Quasar | 7.8×10⁸ M☉ | 241.1 Gly | — | Boötes |
| [ULAS J1120+0641](https://spacecatalog.org/object/ulas-j1120-0641) | Quasar | 2×10⁹ M☉ | 224.4 Gly | — | Leo |
| [Pōniuāʻena](https://spacecatalog.org/object/poniuaena) | Quasar | 1.5×10⁹ M☉ | 206.3 Gly | — | Pegasus |
| [J0439+1634](https://spacecatalog.org/object/uhs-j0439-1634) | Quasar | — | 203.8 Gly | — | Taurus |
| [SDSS J1148+5251](https://spacecatalog.org/object/sdss-j1148-5251) | Quasar | 3×10⁹ M☉ | 202.2 Gly | — | Ursa Major |
| [SDSS J0100+2802](https://spacecatalog.org/object/sdss-j0100-2802) | Quasar | 1.2×10¹⁰ M☉ | 196.9 Gly | — | Pisces |
| [SDSS J1030+0524](https://spacecatalog.org/object/sdss-j1030-0524) | Quasar | — | 196.2 Gly | — | Sextans |
| [PSO J352-15](https://spacecatalog.org/object/pso-j352-15) | Quasar | — | 179.4 Gly | — | Aquarius |
| [J0906+6930](https://spacecatalog.org/object/qso-j0906-6930) | Quasar | — | 163.9 Gly | — | Ursa Major |
| [SMSS J2157-3602](https://spacecatalog.org/object/smss-j2157-3602) | Quasar | 3.4×10¹⁰ M☉ | 138.0 Gly | — | Piscis Austrinus |
| [Q1508+5714](https://spacecatalog.org/object/qso-b1508-5714) | Quasar | — | 125.8 Gly | — | Draco |
| [APM 08279+5255](https://spacecatalog.org/object/apm-08279-5255) | Quasar | — | 112.1 Gly | — | Lynx |
| [PKS 2000-330](https://spacecatalog.org/object/pks-2000-330) | Quasar | — | 107.7 Gly | — | Sagittarius |
| [Q1422+231](https://spacecatalog.org/object/qso-b1422-231) | Quasar | — | 102.2 Gly | — | Boötes |
| [S5 0014+81](https://spacecatalog.org/object/s5-0014-81) | Quasar | 4×10¹⁰ M☉ | 94.16 Gly | — | Cepheus |
| [HS 1946+7658](https://spacecatalog.org/object/hs-1946-7658) | Quasar | — | 82.36 Gly | — | Draco |
| [Cloverleaf quasar](https://spacecatalog.org/object/cloverleaf-quasar) | Quasar | — | 66.23 Gly | — | Boötes |
| [IRAS F10214+4724](https://spacecatalog.org/object/iras-f10214-4724) | Quasar | — | 58.86 Gly | — | Ursa Major |
| [TON 618](https://spacecatalog.org/object/ton-618) | Quasar | 6.6×10¹⁰ M☉ | 56.78 Gly | — | Canes Venatici |
| [4C 71.07](https://spacecatalog.org/object/4c-71-07) | Quasar | — | 55.40 Gly | — | Ursa Major |
| [HE 0435-1223](https://spacecatalog.org/object/he-0435-1223) | Quasar | — | 40.90 Gly | — | Eridanus |
| [Twin Quasar](https://spacecatalog.org/object/twin-quasar) | Quasar | — | 32.72 Gly | — | Ursa Major |
| [PKS 1127-145](https://spacecatalog.org/object/pks-1127-145) | Quasar | — | 26.40 Gly | — | Crater |
| [CTA 102](https://spacecatalog.org/object/cta-102) | Quasar | — | 22.32 Gly | — | Pegasus |
| [3C 454.3](https://spacecatalog.org/object/3c-454-3) | Quasar | — | 17.69 Gly | — | Pegasus |
| [RX J1131-1231](https://spacecatalog.org/object/rx-j1131-1231) | Quasar | — | 12.71 Gly | — | Crater |
| [PKS 0637-752](https://spacecatalog.org/object/pks-0637-752) | Quasar | — | 12.71 Gly | — | Mensa |
| [3C 345](https://spacecatalog.org/object/3c-345) | Quasar | — | 11.28 Gly | — | Hercules |
| [3C 147](https://spacecatalog.org/object/3c-147) | Quasar | — | 10.30 Gly | — | Auriga |
| [3C 279](https://spacecatalog.org/object/3c-279) | Quasar | — | 9.977 Gly | — | Virgo |
| [4C +21.35](https://spacecatalog.org/object/pks-1222-216) | Quasar | — | 7.725 Gly | — | Coma Berenices |
| [3C 48](https://spacecatalog.org/object/3c-48) | Quasar | — | 6.442 Gly | — | Triangulum |
| [H1821+643](https://spacecatalog.org/object/h-1821-643) | Quasar | — | 4.990 Gly | — | Draco |
| [PG 1302-102](https://spacecatalog.org/object/pg-1302-102) | Quasar | — | 4.633 Gly | — | Virgo |
| [PHL 1811](https://spacecatalog.org/object/phl-1811) | Quasar | — | 3.009 Gly | — | Capricornus |
| [PDS 456](https://spacecatalog.org/object/pds-456) | Quasar | — | 2.907 Gly | — | Serpens |
| [3C 273\*](https://spacecatalog.org/object/3c-273-star) | Quasar | 8.86×10⁸ M☉ | 2.451 Gly | — | Virgo |
| [Markarian 231](https://spacecatalog.org/object/mrk-231) | Quasar | — | 607.9 Mly | — | Ursa Major |

## Questions

### What is a quasar?

A supermassive black hole with enough gas falling towards it that the gas itself becomes the brightest thing for millions of light years. Nothing is escaping the hole — the light comes from the disc outside it, heated by friction to the point where it radiates more than the whole surrounding galaxy.

### Why are they all so far away?

Because they are a phase rather than a kind of object, and the phase mostly happened early. Feeding at that rate needs gas delivered fast, which was common when galaxies were still colliding and settling; the same black holes are still there today, mostly quiet, and one of them is at the centre of this galaxy.

### How bright is that, exactly?

The brightest here would outshine the Milky Way by a factor of a thousand. Several are visible in an amateur telescope from billions of light years away, which nothing else in this catalogue can claim.

### Are quasars dangerous?

Not to anything at these distances, and the nearest is 600 million light years away. A quasar is a hazard only to the gas in its own galaxy, where the wind it drives can strip out the material stars would otherwise form from.

### How is the distance measured?

By parallax where the object is near enough — the shift in its apparent position as the Earth crosses its orbit, which is geometry and needs no assumptions. Beyond that, distance is inferred from how bright something of known luminosity appears, and the further out the ladder goes the more the uncertainty grows.

### How firm is the order?

Firmer at the top than at the bottom. Neighbouring rows often sit inside each other's error bars, so a swap between two adjacent entries is a revision rather than a correction. Each object's own page carries the figure with its uncertainty and the method it came from.

### Who worked out what they were?

Maarten Schmidt, in 1963, looking at 3C 273. It had been catalogued as a radio source with a starlike counterpart and a spectrum nobody could identify, until he recognised the lines as ordinary hydrogen shifted far towards the red — which put the object at a distance no star could be, and made it the most luminous thing then known.

### Why does the distance say a different number from the article I read?

Because there are two answers and they are both correct. Press coverage quotes how long the light has been travelling; the figure here is a luminosity distance, which is what the object's brightness implies once the expansion since is accounted for. Each object page carries both.

### Why do some of these vary so violently?

Because their jets point almost at us. A jet aimed at the observer is beamed: the same outburst looks far brighter and appears to run far faster than it would from the side, which is why a handful of entries here can double in a night from across the universe.

### Do the black holes have measured masses?

Some. Where a paper has measured one it is on the object's page; where nobody has, the field is empty rather than estimated. Most quasar masses come from the width of a single emission line and carry a factor of two or three, which is worth knowing before comparing two of them.

## See also

- [The nearest black holes to Earth](https://spacecatalog.org/black-holes/nearest.md)
- [The most massive black holes](https://spacecatalog.org/black-holes/biggest.md)
- [All black holes](https://spacecatalog.org/black-holes.md)

The page itself: https://spacecatalog.org/black-holes/quasars