Puppis A (SNR G260.4−03.4 / RX J0822−4300)
Coordinates, kinematic H I distance (1.3 kpc / 4,240 ly), hypervelocity neutron star RX J0822-4300, and data for Puppis A in Puppis.
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 |
|---|---|---|---|---|---|
| Optical [O III]/N-rich knot integrated magnitude | 13.5 mag | ± 0.6 mag | Integrated optical emission across Baade-Minkowski northern filaments | model-dependent | SIMBAD Astronomical Database (CDS) |
| Heliocentric distance | 4240 ly | ± 650 ly | Syst. 21-cm H I & OH absorption + Gaia 3D dust mapping (1.3 ± 0.2 kpc) (J2016.0) | high-confidence | SIMBAD Astronomical Database (CDS) |
| Apparent shell diameter | 55 arcmin | ± 5 arcmin | ROSAT/Chandra X-ray and radio blast wave (60′ × 50′) | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Puppis A (Cosmic Cannonball Supernova Remnant) at RA 08h 23m 00.00s, Dec -42° 59′ 00.0″ within Puppis, 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
Puppis A (SNR G260.4−03.4) is one of the brightest X-ray supernova remnants in the entire sky, spanning 60 × 50 arcminutes (~65 light-years physically) on the northwestern edge of the larger, foreground Vela Supernova Remnant at a distance of ~4,240 light-years (1.3 ± 0.2 kiloparsecs) in southern Puppis. First discovered as an intense non-thermal radio source in the early 1950s and resolved into fast-moving optical knots by Walter Baade and Rudolph Minkowski in 1954, Puppis A belongs to the rare class of 'oxygen-rich' supernova remnants (alongside Cassiopeia A) whose inner filaments contain virtually pure oxygen, neon, and sulfur synthesized inside a 15–25 solar-mass progenitor star that exploded ~3,700 to 4,500 years ago.
What made Puppis A famous across astrophysics is its compact stellar remnant, RX J0822−4300—nicknamed the 'Cosmic Cannonball.' Discovered in ROSAT and Chandra X-ray images as a thermally glowing 'central compact object' (CCO, a young neutron star with a weak external dipole magnetic field and a 112-millisecond X-ray period), RX J0822−4300 is rocketing toward the southwest at roughly 670 to 1,000 km/s.
In exactly the opposite direction (toward the northeast), oxygen-rich ejecta knots are flying outward at >1,500 km/s—providing a textbook demonstration of conservation of momentum during a lopsided, hydrodynamic neutrino-driven core-collapse explosion.
Practical Visual Observing Guide
- Located at declination −43° in southern Puppis, just 2° north-northwest of the 2.2-magnitude O4 I(n)fp supergiant Naos (ζ Puppis).
- While Puppis A is a powerhouse at soft X-ray energies (0.5–2 keV), its optical emission is confined to a patchwork of 13th-to-15th magnitude nitrogen- and oxygen-rich radiative shock knots (' the Goudis-Meaburn complex') along the northern and eastern rims.
- Visual observers under dark southern skies with 250–400 mm+ telescopes at 50×–100× and an O-III filter can hunt the brightest northeastern filament ridge at RA 08h 24.1m, Dec −42°38′.
Catalog Cross-Identifications & Aliases
Common Aliases: Puppis A · SNR G260.4-03.4 · RX J0822-4300 · Cosmic Cannonball Remnant
| Catalog Authority | Identifier |
|---|---|
| SIMBAD | Puppis A |
| WIKIDATA | Q1078673 |
Related Objects, Comparisons & Guides
Vela Supernova Remnant (Gum 16 & Pulsar)
Coordinates, VLBI pulsar distance (287 pc), 11,000-year core-collapse shell, Pencil Nebula NGC 2736, and observing guide for the Vela SNR.
Cassiopeia A (3C 461 Young Supernova Remnant)
Coordinates, kinematic distance (3.4 kpc), JWST/Chandra ejecta knots, and high-aperture observing guide for Cassiopeia A (3C 461).
Messier 46 (NGC 2437 & NGC 2438 Planetary Pair)
Coordinates, Gaia DR3 distance (1.51 kpc), magnitude 6.1, superposed planetary nebula NGC 2438, and observing guide for M46 in Puppis.
Trigonometric Parallax, Parsecs & Gaia DR3
How trigonometric parallax (d_pc = 1 / p_arcsec), the distance modulus equation, Hipparcos, and Gaia DR3 microarcsecond astrometry measure cosmic distances.
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
- 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
- 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