Messier 110 (NGC 205)
J2000 coordinates, TRGB distance (2.69 Mly), magnitude 8.09, nuclear dust patches, young blue stars, and observing guide for Messier 110 (NGC 205).
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) | 8.09 mag | ± 0.07 mag | Wide-field integrated CCD surface photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Distance in light-years | 2690000 ly | ± 80000 ly | HST Tip of the Red Giant Branch (TRGB) & RR Lyrae variables (824 ± 25 kpc) | definitive | SH0ES Local Distance Ladder Hubble Constant |
| Apparent major axis | 21.9 arcmin | ± 0.8 arcmin | Optical 25 mag/arcsec² isophotal dimensions (21.9′ × 11.0′) | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric radial velocity | -241 km/s | ± 3 km/s | Optical stellar absorption spectroscopy | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Messier 110 (NGC 205 Dwarf Elliptical) at RA 00h 40m 22.08s, Dec +41° 41′ 07.5″ within Andromeda, 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 110 (NGC 205) is the final object ever added to the Messier catalog: although Charles Messier observed it on August 10, 1773, and drew it on his 1807 star chart alongside the Great Andromeda Nebula (M31)—and Caroline Herschel independently discovered it ten years later in August 1783—it was not assigned the designation M110 until Kenneth Glyn Jones proposed it in 1967. Situated 2.69 million light-years away and projected 37 arcminutes northwest of M31's core, M110 is the second-brightest satellite galaxy of Andromeda, spanning ~17,000 light-years across its elongated dE5 halo.
In 1944 Walter Baade used red-sensitive photographic plates on the 100-inch Mount Wilson telescope to resolve M110, M32, and M31's bulge into individual red giant stars for the first time, establishing the foundational astrophysical concept of old, metal-poor 'Population II' versus young, disk 'Population I' stars.
Paradoxically, Baade also discovered that M110 violates the rule that dwarf elliptical galaxies are purely dead, gas-free systems: right near its central nuclear star cluster sit two prominent dark clouds of cold molecular dust and neutral hydrogen alongside a sprinkle of luminous blue OB stars formed within the last 100 million years, while its outer S-shaped isophotes are being tidally twisted by Andromeda's gravity.
Practical Visual Observing Guide
- Positioned 37′ northwest of M31's nucleus on the opposite side of M31's disk from compact M32.
- Although M110 has the same integrated visual magnitude as M32 (V = 8.09 vs 8.08), M110's light is spread over a 21.9′ × 11.0′ oval—six times the area of M32—giving it a much softer, lower surface brightness.
- Easily framed with M31 and M32 in 10×50 binoculars or a wide-field telescope at 20×–45×; in a 300–400 mm (12–16 inch) telescope at 150×–200×, experienced observers can glimpse the tiny dark dust patch (Hodge 73) just 1′ northeast of M110's nuclear star cluster.
Catalog Cross-Identifications & Aliases
Common Aliases: M110 · NGC 205 · UGC 426 · PGC 2429
| Catalog Authority | Identifier |
|---|---|
| MESSIER | M 110 |
| NGC | NGC 205 |
| SIMBAD | M 110 |
| WIKIDATA | Q14366 |
Related Objects, Comparisons & Guides
Andromeda Galaxy (Messier 31 / NGC 224)
Coordinates, Cepheid/TRGB distance (765 kpc / 2.50 Mly), magnitude 3.44, blueshift (−300 km/s), and observing guide for Andromeda (M31).
Messier 32 (NGC 221 Compact Elliptical)
J2000 coordinates, TRGB distance (2.49 Mly), magnitude 8.08, supermassive black hole dynamics, and observing guide for Messier 32 in Andromeda.
Triangulum Galaxy (Messier 33 / NGC 598)
Coordinates, Cepheid/maser distance (859 kpc / 2.80 Mly), low surface brightness (23.0 mag/arcsec²), NGC 604 H II region, and observing guide for M33.
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.
Astronomical Catalogs Explained (M, NGC, Gaia)
How astronomical designations work across the Messier (M), NGC/IC, Bayer/Flamsteed, Henry Draper (HD), Hipparcos (HIP), and Gaia DR3 catalogs.
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