Messier 105 (NGC 3379)
J2000 coordinates, SBF/TRGB distance (34.2 Mly), magnitude 9.28, E1 standard luminosity profile, Leo I trio, and observing guide for Messier 105.
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) | 9.28 mag | ± 0.07 mag | de Vaucouleurs R^(1/4) standard surface photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Distance in light-years | 34200000 ly | ± 1100000 ly | HST Tip of the Red Giant Branch (TRGB) + surface-brightness fluctuations (10.5 ± 0.35 Mpc) | definitive | SH0ES Local Distance Ladder Hubble Constant |
| Apparent major axis | 5.4 arcmin | ± 0.3 arcmin | Optical isophotal dimensions (5.4′ × 4.8′) | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric recession velocity | 911 km/s | ± 2 km/s | Optical stellar absorption spectroscopy | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Messier 105 (NGC 3379 Leo I Elliptical) at RA 10h 47m 49.60s, Dec +12° 34′ 53.9″ within Leo, 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 Pierre Méchain on March 24, 1781—just four days after he found nearby M95 and M96—and added to the Messier catalog by Helen Sawyer Hogg in 1947 from Méchain's correspondence, Messier 105 (NGC 3379) is the brightest elliptical galaxy in the Leo I (M96) Group at a distance of 34.2 million light-years. In extragalactic astrophysics, NGC 3379 is famous as Gerard de Vaucouleurs's primary observational benchmark for the universal R^(1/4) surface-brightness law of elliptical galaxies, which its radial light profile follows to better than ±0.03 magnitudes over nearly ten magnitudes of surface brightness.
Although M105 appears nearly circular on the sky (classified as E1), dynamical modeling with the SAURON integral-field spectrograph indicates it may actually be a moderately flattened triaxial spheroid or thick lenticular galaxy viewed nearly face-on, containing ~100 billion old, metal-rich stars and a central supermassive black hole of 140 to 200 million solar masses.
Deep Hubble Space Telescope exposures of M105's outer halo resolved a minor metal-poor stellar sub-population alongside a few young stars formed within the past few hundred million years, likely accreted from the giant 650,000-light-year Leo H I Ring that loops around M105 and its close companion lenticular galaxy NGC 3384.
Practical Visual Observing Guide
- Located 50′ north-northeast of M96 in central Leo.
- M105 forms the centerpiece of one of the finest galaxy trios for backyard telescopes: within a single 10-arcminute circle sit three completely different galaxy types—the round E1 elliptical M105 (mag 9.3), the elongated S0 lenticular NGC 3384 (mag 9.9, just 7′ ENE), and the 11.9-mag background spiral NGC 3389 (at 60 million light-years, forming a right triangle to the southeast).
- Even an 80–100 mm telescope shows M105 and NGC 3384 side by side, while a 150–200 mm scope adds NGC 3389 to complete the trio.
Catalog Cross-Identifications & Aliases
Common Aliases: M105 · NGC 3379 · UGC 5902 · PGC 32256
| Catalog Authority | Identifier |
|---|---|
| MESSIER | M 105 |
| NGC | NGC 3379 |
| SIMBAD | M 105 |
| WIKIDATA | Q14360 |
Related Objects, Comparisons & Guides
Messier 96 (NGC 3368 Leo I Group Anchor)
J2000 coordinates, HST Cepheid distance (34.9 Mly), magnitude 9.25, asymmetric dusty spiral arms, double bar, and observing guide for Messier 96 in Leo.
Messier 95 (NGC 3351 Theta-Shaped Spiral)
J2000 coordinates, HST Cepheid distance (32.6 Mly), magnitude 9.73, textbook SB(r)b bar and ring, circumnuclear knots, and observing guide for Messier 95.
Messier 49 (NGC 4472 Virgo Giant Elliptical)
J2000 coordinates, SBF distance (55.9 Mly), magnitude 8.40, globular cluster halo, X-ray bow shock, and observing guide for Messier 49 in Virgo.
Angular Size, Separation & Field of View
How angular diameter (degrees, arcminutes, arcseconds), spherical angular separation, and small-angle physical diameter relate to telescope field of view.
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