Procyon (Alpha Canis Minoris)
Coordinates, Hipparcos parallax (284.56 mas, 11.46 ly), magnitude 0.34, Procyon B white dwarf companion, and observing guide for Procyon.
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 (Procyon A) | 0.34 mag | ± 0.01 mag | Johnson UBV photoelectric photometry | definitive | Hipparcos New Reduction Catalog |
| Trigonometric parallax | 284.56 mas | ± 1.26 mas | Hipparcos New Reduction + HST WFPC2/WFC3 astrometry (3.514 ± 0.015 pc) (J2000.0) | definitive | Hipparcos New Reduction Catalog |
| Distance in light-years | 11.46 ly | ± 0.05 ly | Derived from parallax 284.56 ± 1.26 mas | definitive | Hipparcos New Reduction Catalog |
| Primary stellar mass (Procyon A) | 1.478 M☉ | ± 0.012 M☉ | HST 40.84-year binary orbit (Bond et al. 2015; Procyon B = 0.592 ± 0.006 M☉) | definitive | SIMBAD Astronomical Database (CDS) |
| Photospheric radius (Procyon A) | 2.048 R☉ | ± 0.025 R☉ | VLTI/VINCI & Mark III optical interferometry (5.448 ± 0.053 mas) | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Procyon (Alpha Canis Minoris Subgiant) at RA 07h 39m 18.12s, Dec +05° 13′ 30.0″ within Canis Minor, 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
Procyon (Alpha Canis Minoris, from the Greek meaning 'before the dog' because at northern latitudes it rises shortly ahead of the Dog Star Sirius) is the eighth-brightest star in the night sky at magnitude 0.34. Lying just 3.514 ± 0.015 parsecs (11.46 light-years) away, it is one of our Solar System's nearest neighbors and forms the eastern vertex of the Winter Triangle alongside Sirius and Betelgeuse.
Although classified as an F5 IV–V star with a mass of 1.478 solar masses and an effective temperature of 6,530 K, Procyon A is nearly seven times more luminous than the Sun (6.93 solar luminosities) and has swollen to 2.05 solar radii—indicating that it has nearly exhausted the hydrogen fuel in its core and is beginning to evolve off the main sequence into a subgiant. Space-based photometry with the MOST and WIRE satellites detected solar-like p-mode acoustic oscillations across its convective envelope.
Like Sirius, Procyon is an astrometric binary whose unseen companion was predicted by Arthur Auwers in 1862 from proper-motion perturbations and visually discovered by John Martin Schaeberle in 1896 using the 36-inch Lick refractor. Procyon B is a dim magnitude 10.82 DQZ white dwarf (0.592 solar masses, radius 0.0123 solar radii) with carbon and trace metal lines in a helium-dominated atmosphere, orbiting Procyon A every 40.84 years at a mean separation of 15.0 AU.
Practical Visual Observing Guide
- Shines with a warm yellowish-white hue 25° northeast of Sirius and 26° east of Betelgeuse, anchoring the compact two-star constellation Canis Minor alongside 2.9-magnitude Gomeisa (β CMi).
- Splitting magnitude 10.82 Procyon B from magnitude 0.34 Procyon A (a 10.5-magnitude / 15,000:1 brightness ratio at only 2.2″ to 5.2″ separation) is far harder than splitting Sirius B, requiring a 250–350 mm telescope under sub-arcsecond seeing near maximum elongation.
Catalog Cross-Identifications & Aliases
Common Aliases: α Canis Minoris · Procyon A & B · HD 61421 · HIP 37279
| Catalog Authority | Identifier |
|---|---|
| HIP | HIP 37279 |
| HD | HD 61421 |
| SIMBAD | * alf CMi |
| WIKIDATA | Q13034 |
Related Objects, Comparisons & Guides
Sirius (Alpha Canis Majoris Binary)
Coordinates, Hipparcos parallax (379.21 mas, 8.60 ly), magnitude −1.46, Sirius B white dwarf orbit, and observing guide for Sirius.
Betelgeuse (Alpha Orionis Red Supergiant)
Coordinates, competing optical vs radio distances (168 vs 222 pc), radius, Great Dimming physics, and observing guide for Betelgeuse.
Pollux (Beta Geminorum Planet-Hosting Giant)
Coordinates, Hipparcos parallax (96.54 mas, 33.78 ly), magnitude 1.14, exoplanet Pollux b (Thestias), and observing guide for Pollux in Gemini.
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.
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
- Hipparcos New Reduction Catalog (2007 New Reduction): van Leeuwen, F. 2007, A&A, 474, 653 (Validation of the new Hipparcos reduction) — ESA / van Leeuwen (2007)
- 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