Open Clusters · Constellation Cassiopeia

Messier 52 (NGC 7654)

Coordinates, Gaia DR3 distance (1.49 kpc), magnitude 6.9, heavy differential dust extinction, and observing guide for M52 in Cassiopeia.

Right Ascension (J2000.0)23h 24m 16.00s
Declination (J2000.0)+61° 35′ 36.0″
Primary ClassificationYoung rich open star cluster
Best Observing SeasonAutumn to Early Winter (September–January)

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.

Astrometric, Photometric, and Physical Parameters for Messier 52 (NGC 7654)
ParameterValueUncertaintyMethod & EpochQuality StatusSource Archive
Integrated visual magnitude (V)6.9 mag± 0.2 magIntegrated CCD aperture photometryhigh-confidenceRevised New General Catalogue and Index Catalogue (RNGC/IC)
Heliocentric distance4860 ly± 130 lyGaia DR3 astrometric parallax of ~1,100 members (1.49 ± 0.04 kpc) (J2016.0)definitiveESA Gaia Archive — Data Release 3
Apparent diameter13 arcmin± 1 arcminVisual and photographic core extenthigh-confidenceRevised New General Catalogue and Index Catalogue (RNGC/IC)
Main-sequence turnoff age0.065 Gyr± 0.015 GyrDifferential-reddening-corrected Gaia DR3 B-star isochronemodel-dependentESA Gaia Archive — Data Release 3
Measurement Uncertainties & Competing Solutions: Severe, patchy interstellar dust across M52 (E(B−V) ranging from 0.45 to 0.85 mag across 13 arcminutes) historically caused photometric distances to vary from 1.1 to 2.1 kpc until Gaia DR3 parallaxes fixed it at 1.49 ± 0.04 kpc.

J2000 Equatorial Sky Chart & Culmination Altitude

The chart below plots Messier 52 (NGC 7654 Salt-and-Pepper Cluster) at RA 23h 24m 16.00s, Dec +61° 35′ 36.0″ within Cassiopeia, 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.

J2000 Equatorial Sky Position (Cassiopeia) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 68° 40°N Lat 0° 30°S Lat RA: 23h 24m 16.00s Dec: +61° 35′ 36.0″ Epoch: J2000.0 · V = 6.9 mag First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Astrophysical Context & Structure

Messier 52 (NGC 7654) is a rich, compressed young open cluster located 4,860 light-years (1.49 ± 0.04 kiloparsecs) away in the Perseus Spiral Arm along the western border of Cassiopeia. Discovered by Charles Messier on September 7, 1774, while tracking the Great Comet of 1774, M52 packs over 1,100 confirmed stars into a 13-arcminute (~19-light-year) diameter with a high central core density of ~55 stars per cubic parsec.

Because our sightline to M52 skims directly through the dusty midplane of the Milky Way, foreground interstellar clouds absorb between 1.4 and 2.6 magnitudes of visual light across different sectors of the cluster. If that dust veil were removed, M52 would shine near naked-eye magnitude 4.8. At an age of ~65 million years, the cluster is rich in pulsating Slowly Pulsating B (SPB) stars, Classical Be emission-line stars, and Delta Scuti variables.

On the western edge of M52 shines the luminous 7.8-magnitude F9 Ib yellow-orange supergiant BD+60 2532, while just 35 arcminutes southwest sits the famous Bubble Nebula (NGC 7635)—making the M52/Bubble Nebula pair one of the premier wide-field astrophotography and visual targets in the northern autumn sky.

Practical Visual Observing Guide

Minimum Instrument10×50 binoculars
Recommended Magnification60×–140×
Best Evening SeasonAutumn to Early Winter (September–January)
  • Easy to locate via the Cassiopeia W: draw a line from Alpha Cassiopeiae (Schedar) through Beta Cassiopeiae (Caph) and extend an equal distance (~6°) further northwest, passing 40′ south of 5th-magnitude 4 Cassiopeiae.
  • In 10×50 binoculars M52 appears as a fuzzy 6.9-magnitude fan clinging to its bright 7.8-magnitude western anchor star.
  • Through a 120–200 mm telescope at 70×–140×, hundreds of 11th-to-13th magnitude stars resolve into a triangular or kidney-shaped cloud; pan 35′ southwest with an O-III or UHC filter to hunt the Bubble Nebula (NGC 7635).

Catalog Cross-Identifications & Aliases

Common Aliases: M52 · NGC 7654 · Scorpion Cluster

Cross-Catalog Identifiers for Messier 52 (NGC 7654)
Catalog AuthorityIdentifier
MESSIERM 52
NGCNGC 7654
SIMBADM 52
WIKIDATAQ11455
Related Object · Cassiopeia

Bubble Nebula (NGC 7635 in Cassiopeia)

Coordinates, Gaia DR3 distance (2.52 kpc), O6.5f star BD+60 2522 off-center wind cavity, and observing guide for NGC 7635 in Cassiopeia.

Related Object · Cassiopeia

Owl Cluster (NGC 457 / ET Cluster)

Coordinates, Gaia DR3 distance (2.88 kpc), magnitude 6.4, Phi Cassiopeiae supergiant eyes, and observing guide for NGC 457 in Cassiopeia.

Related Object · Perseus

Double Cluster (NGC 869 & NGC 884)

Coordinates, Gaia DR3 distance (2.29 kpc), age 14 Myr, supergiant population, and observing guide for NGC 869 and NGC 884 in Perseus.

Reference Guide

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