Heart-Shaped Cluster (Messier 50 / NGC 2323)
Coordinates, Gaia DR3 distance (961 pc), magnitude 5.9, crimson giant HD 52938 contrast, and observing guide for Messier 50 in Monoceros.
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) | 5.9 mag | ± 0.1 mag | Wide-aperture integrated photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric distance | 3135 ly | ± 55 ly | Gaia DR3 astrometric parallax of ~600 members (961 ± 17 pc) (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Apparent diameter | 16 arcmin | ± 1.5 arcmin | Visual and Gaia DR3 member core extent | high-confidence | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Main-sequence turnoff age | 0.14 Gyr | ± 0.02 Gyr | Gaia DR3 B6 V turnoff & red-giant isochrone fitting | high-confidence | ESA Gaia Archive — Data Release 3 |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Heart-Shaped Cluster (Messier 50 / NGC 2323) at RA 07h 02m 47.50s, Dec -08° 20′ 16.0″ within Monoceros, 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
Messier 50 (NGC 2323, the Heart-Shaped Cluster) is a rich, picturesque winter open cluster located 3,135 light-years (961 ± 17 parsecs) away in southern Monoceros, near the border with Canis Major. Probably discovered by Giovanni Domenico Cassini at Paris Observatory before 1711 (as reported by his son Jacques Cassini in 1740), M50 was independently recovered by Charles Messier on April 5, 1772, while charting Halley-like comet paths.
Spanning 16 arcminutes across the sky (~15 light-years in physical core width), M50 contains roughly 600 confirmed stars and a total dynamical mass near 1,000 solar masses. At an age of ~140 million years, its upper main sequence is populated by hot blue-white B6 to B9 stars, while several evolved stars have transitioned onto the red-giant branch.
Visually, M50's two curving northern lobes converge southward into a sharp apex—forming the unmistakable outline of a valentine heart or arrowhead—accentuated 7 arcminutes south of the center by the vivid 7.8-magnitude K3.5 II–III orange-red bright giant HD 52938.
Practical Visual Observing Guide
- Exceptionally easy to find via a geometric star-hop: draw a line from brilliant Sirius (α Canis Majoris) to Procyon (α Canis Minoris); M50 sits slightly over one-third of the way along that line, 9.5° northeast of Sirius and 4° north of Theta Canis Majoris.
- In 10×50 binoculars M50 appears as a bright, triangular 5.9-magnitude knot with its southern red giant already hinting at color.
- Through a 100–150 mm telescope at 50×–100×, the heart-shaped figure of ~100 blue-white stars and the ruby-orange beacon of HD 52938 on the southern rim are striking.
Catalog Cross-Identifications & Aliases
Common Aliases: M50 · NGC 2323 · Heart-Shaped Cluster
| Catalog Authority | Identifier |
|---|---|
| MESSIER | M 50 |
| NGC | NGC 2323 |
| SIMBAD | M 50 |
| WIKIDATA | Q11420 |
Related Objects, Comparisons & Guides
Little Beehive Cluster (Messier 41 / NGC 2287)
Coordinates, Gaia DR3 distance (716 pc), magnitude 4.5, central K3 II orange giant HD 49091, and Sirius finder guide for M41 in Canis Major.
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.
Rosette Nebula (NGC 2237 & NGC 2244 Cluster)
Coordinates, Gaia DR3 distance (1.42 kpc), central wind-blown cavity around NGC 2244 O-stars, and observing guide for the Rosette Nebula in Monoceros.
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.
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.
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
- 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
- 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