M52 is a magnitude +7.2 open cluster located in western Cassiopeia. This excellent grouping of stars is one of the best clusters in the northern Milky Way, with some 200 members spread across 13 arc minutes of apparent sky. It can be seen in binoculars and is a wonderful sight through telescopes, appearing rich and bright with dozens of mainly white stars visible.

M52 was one of Charles Messier's original discoveries, which he cataloged on September 7, 1774. He spotted it when a comet he was observing passed close by. The cluster is easy to find since it's located one degree south of star, 4 Cas (mag. +5.0). An imaginary line from Schedar (α Cas - mag. +2.2) extending towards Caph (β Cas - mag. +2.3) and again for about the same distance also leads to M52.

Messier 52 Open Cluster (credit:- NOAO/AURA/NSF)

Finder Chart for M52 (credit:- freestarcharts)

Finder Chart for M52 - pdf format (credit:- freestarcharts)

Through 10x50 binoculars, M52 appears somewhat fan, kidney or V shaped with a prominent 8th magnitude yellow star at the southwest corner. An 80mm (3.1-inch) telescope reveals a concentrated cluster of mostly faint members, that's best seen using averted vision. It appears like a sprinkling of salt and pepper, spread over an area just less than half the apparent size of the full Moon. A small increase in aperture, enhances the fan shape and the overall appearance of the cluster. A 150mm (6-inch) scope, reveals at least a dozen stars surrounded by a round diffuse haze, with the bright yellow star prominent. With the help of averted vision, the background haze resolves into about 50 or so faint stars. In even larger telescopes, M52 is brilliant with dozens of stars clearly visible. Due to interstellar light absorption, the distance to M52 is difficult to accurately determine. Estimates range between 3,000 and 7,000 light-years. Assuming a value of 7,000 light-years, then M52 has a spatial diameter of 26.5 light-years. It's estimated to be 35 million years old.

M52 is best seen from the Northern Hemisphere during August, September and October, where it appears high in the sky or even overhead from some locations. From latitudes greater than 28N, the cluster is circumpolar. Along with NGC 457 and NGC 7789, it's one of the finest clusters in the northern Milky Way. NGC 7635, the Bubble Nebula, an unusual emission nebula is 0.5 degrees southwest of M52.

M52 Data Table

Messier52
NGC7654
Object TypeOpen Cluster
ConstellationCassiopeia
Distance (light-years)7,000
Apparent Mag.+7.2
RA (J2000)23h 24m 50s
DEC (J2000)61d 36m 24s
Apparent Size (arc mins)13 x 13
Radius (light-years)13.25
Age (years)35 Million
Number of Stars200
Other NameCollinder 455

Sky Highlights - July 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for July

Meteor Shower
Southern Delta Aquariids (Aquarids) meteor shower peaks on July 29

Northern Hemisphere
Evening
West:- Mercury (mag. -0.5 to +0.3) (second half of month)
Southwest:- Jupiter (mag. -2.0)
South:- Saturn (mag. +0.2)
Midnight
West:- Jupiter
South:- Saturn
East:- Neptune (mag. +7.8)
Morning
Southwest:- Saturn
South:- Neptune
Southeast:- Uranus (mag. +5.8)
East:- Venus (mag. -4.1)

Southern Hemisphere
Evening
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
Midnight
West:- Jupiter
North:- Saturn
East:- Neptune
Morning
West:- Saturn
North:- Neptune
Northeast:- Venus, Uranus

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

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