Centaurus A (NGC 5128 / Arp 153 / Caldwell 77)
J2000 coordinates, TRGB/Cepheid distance (12.4 Mly), magnitude 6.84, warped dust lane, relativistic radio lobes, and observing guide for Centaurus A.
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 |
|---|---|---|---|---|---|
| Integrated visual magnitude (V) | 6.84 mag | ± 0.06 mag | Wide-field integrated CCD aperture photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Distance in light-years | 12400000 ly | ± 400000 ly | HST Tip of the Red Giant Branch (TRGB), Mira variables & Cepheids (3.80 ± 0.12 Mpc) | definitive | SH0ES Local Distance Ladder Hubble Constant |
| Apparent major axis (optical halo) | 25.7 arcmin | ± 1 arcmin | Optical 25 mag/arcsec² isophotal dimensions (25.7′ × 20.0′; radio lobes span ~8°) | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric recession velocity | 547 km/s | ± 5 km/s | H I 21-cm and optical absorption spectroscopy | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Centaurus A (NGC 5128 Active Radio Galaxy) at RA 13h 25m 27.62s, Dec -43° 01′ 08.8″ within Centaurus, 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
Discovered by James Dunlop on April 29, 1826, from Parramatta in New South Wales, Australia, Centaurus A (NGC 5128, Caldwell 77) is the fifth-brightest galaxy in the entire sky (V = 6.84) and the nearest active radio galaxy to Earth at just 12.4 million light-years. In 1949 John Bolton, Gordon Stanley, and Bruce Slee identified NGC 5128 as the optical counterpart of the intense radio source Centaurus A—one of the very first extragalactic radio sources ever linked to an optical galaxy.
Visually and photographically, NGC 5128 is unmistakable: a luminous, golden-yellow giant elliptical or lenticular spheroid is sliced completely in half by a dramatic, S-warped band of dark interstellar dust, molecular clouds, and young pink star clusters. This hybrid anatomy is the aftermath of a cosmic collision roughly 200 to 700 million years ago in which the giant elliptical galaxy devoured a medium-sized spiral galaxy, triggering waves of star formation (including the bright Type Ia supernova SN 1986G) and funneling gas into the core.
At the center of Centaurus A sits a supermassive black hole of 55 ± 10 million solar masses whose sub-parsec jet base was imaged at millimeter wavelengths by the Event Horizon Telescope in 2021. That black hole launches relativistic twin jets at half the speed of light that inflate giant radio synchrotron lobes spanning 8 degrees on the sky (16 times the width of the full Moon, or more than 1.5 million light-years end-to-end).
Practical Visual Observing Guide
- Located 4.4° north of the magnificent globular cluster Omega Centauri (NGC 5139); visible in 7×50 binoculars from any location south of +35°N.
- Even a 60–80 mm refractor at 40×–70× clearly shows the dark 'hamburger bun' dust cleft bisecting the bright round 10′ halo from northwest to southeast!
- In a 250–350 mm telescope at 120×–180×, the dark equatorial dust lane resolves into two parallel dark rifts separated by a bright central lane of young star clouds.
Catalog Cross-Identifications & Aliases
Common Aliases: Centaurus A · NGC 5128 · Arp 153 · Caldwell 77
| Catalog Authority | Identifier |
|---|---|
| NGC | NGC 5128 |
| SIMBAD | NAME Cen A |
| WIKIDATA | Q487255 |
Related Objects, Comparisons & Guides
Southern Pinwheel (Messier 83 / NGC 5236)
J2000 coordinates, Cepheid/TRGB distance (15.2 Mly), magnitude 7.54, barred spiral starburst core, six supernovae, and observing guide for Messier 83.
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.
Sombrero Galaxy (Messier 104 / NGC 4594)
Coordinates, TRGB distance (9.55 Mpc / 31.1 Mly), edge-on dust lane, 1-billion-M☉ central black hole, and observing guide for M104.
Surface Brightness & Extended Objects Guide
Why surface brightness (mag/arcsec²) governs nebula and galaxy visibility more than integrated magnitude, and how exit pupil controls eyepiece contrast.
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.
Scientific Sources & Dataset Provenance
- Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC
- SH0ES Local Distance Ladder Hubble Constant (2022 Baseline Cepheid + SN Ia): Riess, A. G., et al. 2022, ApJL, 934, L7 (A Comprehensive Measurement of the Local Value of the Hubble Constant) — SH0ES Collaboration (HST / JWST)
- 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