Trifid Nebula (Messier 20 / NGC 6514)
Coordinates, Gaia DR3 distance (1.26 kpc), Barnard 85 trisecting dust lanes, HN 40 multiple star, and observing guide for M20 in Sagittarius.
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) | 6.3 mag | ± 0.2 mag | Integrated nebular + HD 164492 cluster photometry | definitive | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
| Heliocentric distance | 4110 ly | ± 130 ly | Gaia DR3 astrometric parallax of HD 164492 multiple system (1.26 ± 0.04 kpc) (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Apparent diameter | 28 arcmin | ± 2 arcmin | Combined emission and northern reflection lobes (28′ × 28′) | high-confidence | Revised New General Catalogue and Index Catalogue (RNGC/IC) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Trifid Nebula (Messier 20 / NGC 6514) at RA 18h 02m 42.00s, Dec -22° 58′ 18.0″ within Sagittarius, 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
The Trifid Nebula (Messier 20, NGC 6514) is a striking three-in-one astrophysical showcase—combining a rose-pink H II emission nebula, a sapphire-blue dust reflection nebula, and a black trisecting dark nebula (Barnard 85)—located 4,110 light-years (1.26 ± 0.04 kiloparsecs) away in Sagittarius, just 1.4 degrees north-northwest of the Lagoon Nebula (M8). Discovered by Charles Messier on June 5, 1764, the object was named 'Trifid' ('divided into three lobes') by Sir John Herschel after William Herschel originally assigned four separate catalog numbers to its bright segments.
Powering the southern emission sphere is the ~300,000-year-old multiple star system HD 164492 (HN 40), dominated by the hot O7.5 III star HD 164492A (~35 solar masses) and the ultra-fast-spinning magnetic helium-strong star HD 164492C. Intense radiation from HD 164492A has blown away surrounding gas except where dense molecular cores shield shadowed dust columns, including a celebrated 0.5-light-year stellar jet (HH 399) protruding from a photoevaporating pillar near the center.
Immediately north of the trisected emission core lies a broad blue reflection cloud illuminated by the 7.4-magnitude F-type supergiant/B-star complex HD 164514, where interstellar dust scatters continuum starlight without ionizing hydrogen.
Practical Visual Observing Guide
- Located just 1.4° north-northwest of the Lagoon Nebula (M8); both M8 and M20 fit together inside a single 2° wide-field telescope eyepiece or binocular view.
- In a 100–200 mm telescope at 50×–100× under dark skies, the three dark dust lanes of Barnard 85 meet near the central triple star HN 40 (Components A, B, and C at magnitudes 7.6, 10.7, and 8.7 separated by 6.2″ and 10.8″).
- Compare the view with and without a UHC filter: the filter dramatically boosts the southern 3-lobed emission cloud, while removing the filter helps reveal the faint northern reflection nebula around HD 164514.
Catalog Cross-Identifications & Aliases
Common Aliases: M20 · NGC 6514 · Trifid Nebula
| Catalog Authority | Identifier |
|---|---|
| MESSIER | M 20 |
| NGC | NGC 6514 |
| SIMBAD | M 20 |
| WIKIDATA | Q11362 |
Related Objects, Comparisons & Guides
Lagoon Nebula (Messier 8 / NGC 6523)
Coordinates, Gaia DR3 distance (1.25 kpc), NGC 6530 cluster, Hourglass core, and observing guide for the Lagoon Nebula (M8) in Sagittarius.
Messier 23 (NGC 6494 Sagittarius Cluster)
Coordinates, Gaia DR3 distance (728 pc), magnitude 5.5, foreground Sagittarius dust lane geometry, and observing guide for M23.
Orion Nebula (Messier 42 / NGC 1976)
Coordinates, VLBI/Gaia distance (412 pc), Trapezium ionizing cluster, and visual observing guide for the Orion Nebula (M42) in Orion.
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.
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.
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