3C 273 (PG 1226+023)
Coordinates, redshift z = 0.1583 (~2.4 billion ly), magnitude 12.85, supermassive black hole accretion, and observing guide for quasar 3C 273.
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 |
|---|---|---|---|---|---|
| Apparent visual magnitude (V) | 12.85 mag | 12.2 to 13.1 mag | Optical CCD & AAVSO monitoring (AGN accretion-disk & jet variability) | definitive | General Catalogue of Variable Stars (GCVS) & AAVSO VSX |
| Cosmological redshift (z) | 0.158339 dimensionless | ± 0.000067 dimensionless | Optical Balmer Hβ, Hγ, Hδ emission-line redshift (Schmidt 1963) | definitive | SIMBAD Astronomical Database (CDS) |
| Luminosity distance (Planck ΛCDM) | 2440000000 ly | ± 40000000 ly | Derived from z = 0.15834 under Planck 2018 flat ΛCDM (~749 Mpc; light-travel time ~2.0 Gyr) | model-dependent | Planck 2018 Cosmological Parameters (PR3) |
| Central black hole mass | 886000000 M☉ | ± 187000000 M☉ | Broad-line reverberation mapping & VLTI GRAVITY interferometry (~3–9 × 10^8 M☉) | model-dependent | SIMBAD Astronomical Database (CDS) |
| Bolometric quasar luminosity | 4100000000000 L☉ | ± 500000000000 L☉ | Multi-wavelength SED integration (M_V ≈ −26.7, ~4.1 × 10^12 L☉) | high-confidence | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots 3C 273 (Brightest Quasar in Virgo) at RA 12h 29m 06.70s, Dec +02° 03′ 08.6″ within Virgo, 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
3C 273 (the 273rd object in the Third Cambridge Catalogue of Radio Sources) is the optically brightest quasar in Earth's sky (magnitude 12.85) and the first quasar ever identified. In 1962 Cyril Hazard used lunar occultations with the Parkes Radio Telescope in Australia to pinpoint the radio source's exact position, and on February 5, 1963, Maarten Schmidt at Palomar Observatory realized that the mysterious emission lines in the spectrum of its 12.8-magnitude blue 'star' were ordinary hydrogen Balmer lines redshifted by Δλ/λ = 0.1583—indicating a recession velocity of ~44,000 km/s (~15% of the speed of light).
At a luminosity distance of ~749 megaparsecs (2.44 billion light-years, lookback time ~2.0 billion years), 3C 273 has an absolute visual magnitude of M_V ≈ −26.7. If 3C 273 were placed at the distance of Pollux (10 parsecs / 33 light-years from Earth), it would shine in our sky at magnitude −26.7—precisely as bright as our daytime Sun! Its total bolometric output exceeds 4 trillion solar luminosities, roughly 100 times the light of the entire Milky Way galaxy, emitted from an accretion disk scarcely larger than our Solar System feeding a ~300-to-900-million-solar-mass black hole.
Because 3C 273 is so distant yet bright enough for Gaia DR3 (which measured its proper motion to be zero within 0.01 milliarcseconds per year), it serves as the primary optical anchor aligning the International Celestial Reference Frame (ICRF) between radio VLBI and space optical astrometry.
Practical Visual Observing Guide
- 3C 273 is by far the most distant object accessible to a backyard 150–200 mm (6–8 inch) amateur telescope: at magnitude 12.85, its light has been traveling through space for roughly 2 billion years (since the Paleoproterozoic Era on Earth, long before multicellular life evolved).
- Located in southern Virgo ~3.5° northeast of Zavijava (β Virginis) and ~4° northwest of Porrima (γ Virginis); use a detailed 15-arcminute finder chart at 120×–180× to identify its blue-white stellar point.
Catalog Cross-Identifications & Aliases
Common Aliases: PG 1226+023 · HIP 60936
| Catalog Authority | Identifier |
|---|---|
| GAIADR3 | 3700386905605085952 |
| HIP | HIP 60936 |
| SIMBAD | 3C 273 |
| WIKIDATA | Q229318 |
Related Objects, Comparisons & Guides
Messier 87 (Virgo A Giant Elliptical Galaxy)
Coordinates, distance (16.4 Mpc / 53.5 Mly), EHT 6.5-billion M☉ black hole M87*, relativistic jet, and observing guide for Messier 87.
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*.
Spica (Alpha Virginis Ellipsoidal Binary)
Coordinates, Hipparcos distance (250 ly), 4.01-day close B-star binary, precession discovery history, and observing guide for Spica.
Spring Galaxy Season: Ursa Major to Virgo
Spring galaxy observing guide from Ursa Major (M81, M82, Whirlpool M51) across Coma/Virgo to giant elliptical M87, the Sombrero Galaxy (M104), and 3C 273.
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.
Celestial Coordinates (RA & Dec) Explained
Practical reference to J2000 equatorial coordinates: Right Ascension (RA in hours, minutes, seconds), Declination (Dec in degrees), and sexagesimal conversion.
Scientific Sources & Dataset Provenance
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC
- Planck 2018 Cosmological Parameters (PR3) (PR3 (2020 A&A 641, A6)): Planck Collaboration, Aghanim, N., et al. 2020, A&A, 641, A6 — ESA / Planck Collaboration
- 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