TON 618
Reference data for TON 618: redshift z = 2.219, ~40–66 billion solar mass black hole in Canes Venatici, and 140-trillion-solar-luminosity output.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Cosmological Redshift (z) | 2.219 dimensionless | ± 0.002 dimensionless | Standard astrophysical catalog determination | definitive | SIMBAD Astronomical Database (CDS) |
| Light-Travel Distance | 10800000000 ly | ± 100000000 ly | Lookback distance at z = 2.219; comoving distance is ~18.2 billion light-years. | definitive | SIMBAD Astronomical Database (CDS) |
| Apparent Magnitude (V) | 15.9 mag | ± 0.1 mag | Optical Johnson V-band photometry | definitive | SIMBAD Astronomical Database (CDS) |
| Absolute Magnitude | -30.7 mag | ± 0.2 mag | Standard astrophysical catalog determination | high-confidence | SIMBAD Astronomical Database (CDS) |
| Black Hole Mass | 40700000000 M☉ | ± 15000000000 M☉ | Broad-line virial estimates range from ~40.7 billion M☉ (C IV, Ge et al. 2019) to ~66 billion M☉ (Hβ, Shemmer et al. 2004). | model-dependent | SIMBAD Astronomical Database (CDS) |
| Bolometric Luminosity | 140000000000000 L☉ | ± 20000000000000 L☉ | Approximately 5.4 × 10⁴⁷ erg/s, outshining over a thousand Milky Way galaxies. | high-confidence | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots TON 618 — Ultramassive Black Hole & Quasar at RA 12h 31m 47.27s, Dec +31° 00′ 05.8″ within Canes Venatici, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
First cataloged in 1957 by Mexican astronomers Braulio Iriarte and Enrique Chavira on Schmidt plates at Tonantzintla Observatory as a faint blue star near the north galactic pole (#618 in the Tonantzintla bulletin), TON 618 was recognized as a radio source in 1970 and spectroscopically confirmed by Marie-Hélène Ulrich as a distant quasar at redshift z = 2.219. The light reaching our telescopes today departed its accretion disk roughly 10.8 billion years ago, when the universe was barely three billion years old.
Infrared spectroscopy of the broad H-beta emission line by Ohad Shemmer and collaborators in 2004, junto with ultraviolet C IV broad-line measurements by XueGe et al. in 2019, revealed gas clouds in the broad-line region whipping around the central engine at over 7,000 to 10,500 kilometers per second. Virial mass calibrations yield an ultramassive black hole between 40.7 billion and 66 billion solar masses—meaning its event horizon alone spans roughly 800 to 1,300 astronomical units in radius, more than twenty times the size of Neptune's orbit.
Radiating at an astonishing 140 trillion solar luminosities (absolute magnitude -30.7), the quasar completely overwhelms the starlight of its surrounding galaxy. Deep ALMA submillimeter and VLT/MUSE integral-field observations reveal that TON 618 sits at the center of an enormous 300,000-light-year Lyman-alpha nebula, fed by converging filaments of cold intergalactic gas and multiple merging companion galaxies.
Practical Visual Observing Guide
- Shines at visual magnitude V = 15.9 near the border of Canes Venatici and Coma Berenices.
- Can be captured in 5-minute exposures with 6-inch+ amateur astrographs, and glimpsed visually in 16-inch to 20-inch Dobsonians under dark skies—making it one of the most distant objects visible to the human eye.
- Its extreme redshift (z = 2.219) shifts the ultraviolet Lyman-alpha line (121.6 nm) right into the blue optical band at 391 nm.
Catalog Cross-Identifications & Aliases
Common Aliases: Tonantzintla 618 · QSO B1228+3128 · FBQS J1231+3101
| Catalog Authority | Identifier |
|---|---|
| SIMBAD | Tonantzintla 618 |
Related Objects, Comparisons & Guides
3C 273 (Brightest Quasar in Virgo)
Coordinates, redshift z = 0.1583 (~2.4 billion ly), magnitude 12.85, supermassive black hole accretion, and observing guide for quasar 3C 273.
M87* Black Hole (Powehi) — First EHT Shadow
Reference data for the M87* supermassive black hole: 6.5 billion solar masses, 42-microarcsecond shadow diameter, and relativistic jet physics.
Sagittarius A* (Galactic Center Black Hole)
Coordinates, GRAVITY S2 stellar orbit distance (8,277 pc) & mass (4.297 × 10^6 M☉), EHT 51.8 μas shadow, and Galactic Center guide for Sgr A*.
Apparent vs Absolute Magnitude Explained
Understand the logarithmic Pogson astronomical magnitude scale, apparent visual magnitude (m), absolute magnitude (M at 10 parsecs), and bolometric corrections.
Measurement Uncertainty & Optics in Astronomy
How random vs systematic errors, asymmetric error bars, model dependencies, and optical aperture/exit-pupil limits shape astronomical measurements.
Scientific Sources & Dataset Provenance
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg