Messier 92 (NGC 6341)
Coordinates, Gaia distance (8.50 kpc), metal-poor [Fe/H] = −2.31 dex, and observing guide for ancient globular cluster Messier 92 in Hercules.
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 | ± 0.05 mag | Integrated CCD photometry | definitive | Catalog of Parameters for Milky Way Globular Clusters |
| Heliocentric distance | 8500 pc | ± 90 pc | Gaia EDR3 + HST kinematics (Vasiliev & Baumgardt 2021) (J2016.0) | high-confidence | Catalog of Parameters for Milky Way Globular Clusters |
| Metallicity [Fe/H] | -2.31 dex | ± 0.05 dex | High-dispersion optical/NIR giant spectroscopy | definitive | Catalog of Parameters for Milky Way Globular Clusters |
| Isochrone age | 13.3 Gyr | ± 0.6 Gyr | JWST NIRCam + HST ACS lower-main-sequence & turnoff calibration | model-dependent | JWST / MAST Science Archive & Mission Documentation |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Messier 92 (NGC 6341 in Hercules) at RA 17h 17m 07.40s, Dec +43° 08′ 09.4″ within Hercules, 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 92 (NGC 6341) is one of the oldest and most metal-poor globular clusters in the Milky Way, situated 8.50 ± 0.09 kiloparsecs (27,700 light-years) away in northern Hercules. Discovered by Johann Elert Bode in December 1777 and independently recovered by Charles Messier in March 1781, M92 is often overshadowed by nearby M13 yet is nearly as luminous intrinsically, packing roughly 330,000 solar masses into a tightly concentrated Shapley-Sawyer Class IV profile.
With an iron abundance of [Fe/H] = −2.31 dex—less than 0.5% of the solar iron-to-hydrogen ratio—M92 formed from gas enriched by only the earliest generations of massive supernovae. Because of its extreme antiquity, the James Webb Space Telescope selected M92 for its Early Release Science program, resolving faint hydrogen-burning stars down to 0.1 solar masses and calibrating main-sequence turnoff ages at 13.3 ± 0.6 billion years.
Curiously, Earth's axial precession carries the north celestial pole within less than 1° of M92 around 14,000 years in the past and again roughly 12,000 years in the future, making M92 a periodic 'polar cluster' during the 25,772-year precession cycle.
Practical Visual Observing Guide
- Located 6.3° north-northeast of Pi Herculis and about 9° northeast of M13, forming the apex of a flat triangle with Eta and Pi Herculis.
- At magnitude 6.3, M92 is an easy binocular object and shows a noticeably brighter, tighter central core than M13 in 80–100 mm telescopes.
- Use 150×–220× in a 150 mm or larger telescope to resolve the blazing central condensation and the chains of 12th-magnitude red giants radiating into the outer halo.
Catalog Cross-Identifications & Aliases
Common Aliases: M92 · NGC 6341
| Catalog Authority | Identifier |
|---|---|
| MESSIER | M 92 |
| NGC | NGC 6341 |
| SIMBAD | M 92 |
| WIKIDATA | Q14089 |
Related Objects, Comparisons & Guides
Messier 13 (Hercules Globular Cluster)
Coordinates, Gaia DR3 distance (7.42 kpc), visual magnitude 5.78, and Keystone finder guide for Messier 13 (NGC 6205) in Hercules.
Omega Centauri (NGC 5139 Cluster)
Coordinates, Gaia DR3 distance (5.43 kpc), magnitude 3.68, and multi-population core data for Omega Centauri (NGC 5139) in Centaurus.
47 Tucanae (NGC 104 Globular Cluster)
Coordinates, Gaia distance (4.52 kpc), magnitude 4.09, millisecond pulsar core, and observing guide for 47 Tucanae (NGC 104).
Messier 13 vs Messier 92 Hercules Globulars
Compare the twin Hercules globular clusters Messier 13 (NGC 6205) and Messier 92 (NGC 6341) in age, metallicity, core concentration, and eyepiece resolution.
Globular Cluster Resolution & Southern Gems
How to resolve ancient halo globular clusters—Messier 13, Messier 92, Omega Centauri, and 47 Tucanae—from outer red giants to dense Shapley-Sawyer cores.
Small-Telescope Messier Objects Tour (80–150mm)
Curated seasonal tour of flagship Messier clusters, nebulae, and galaxies optimized for 80 mm to 150 mm (3-inch to 6-inch) refractors and reflectors.
Astronomical Epochs (J2000, J2016) & Precession
Why celestial coordinates specify a reference epoch (J2000.0 vs Gaia J2016.0), how axial precession shifts RA/Dec over time, and how ICRS anchors astrometry.
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.
Messier Catalog (M) Objects & Cross-Reference
Guide and cross-walk to Charles Messier's flagship deep-sky catalog (M1 to M104 in FastAstro), linking Messier numbers to NGC IDs, distances, and magnitudes.
Milky Way Globular Clusters Reference Catalog
Cross-reference catalog of Milky Way halo globular clusters (Harris / Gaia EDR3) comparing Messier 13, Omega Centauri, Messier 92, and 47 Tucanae.
Scientific Sources & Dataset Provenance
- Catalog of Parameters for Milky Way Globular Clusters (2010 / 2021 Gaia EDR3 revision): Harris, W. E. 1996 (2010 ed.), AJ, 112, 1487; Vasiliev, E. & Baumgardt, H. 2021, MNRAS, 505, 5978 — McMaster University / Gaia EDR3 Cluster Survey
- 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
- JWST / MAST Science Archive & Mission Documentation (Cycle 1–4 Public Releases (2022–2026)): Rigby, J., et al. 2023, PASP, 135, 048001 (The Science Performance of JWST as Characterized in Commissioning) — NASA / ESA / CSA / STScI