NGC 663, mag. +7.1, is a young open cluster that's one of a number of bright clusters that can be seen with binoculars in the constellation of Cassiopeia. It contains at least 80 stars visible in amateur telescopes spread over a diameter of 16 arc minutes. A 100mm (4-inch) scope reveals a bright rich grouping immersed in a hazy glow with many stars resolvable. NGC 663 is striking in larger scopes appearing reasonably concentrated towards the centre with dozens of stars spread across the cluster face. Double star Struve 152 is a cluster member.

NGC 663 (credit - Hunter Wilson)

NGC 663 is located 3 degrees northeast of Ruchbah (δ Cas - mag. +2.7) and 3 degrees southwest of epsilon Cas (ε Cas - mag. +3.4). Positioned just north of the cluster is NGC 654 (mag. +6.5) with NGC 659 (mag. +7.9) to the south. Also located nearby next to Ruchbah is M103 (mag. +7.4). All of these open clusters are visible in binoculars.

From most northern temperate latitudes NGC 663 is circumpolar and therefore visible all year round; it appears highest in the sky during October, November and December. From Southern Hemisphere latitudes the cluster appears at best low above the northern horizon and from some more southerly locations it never even rises at all.

NGC 663 is located 7,000 light-years distant. It's estimated to be 20 Million years old and is number 10 in the Caldwell catalogue. The cluster was discovered by William Herschel on November 3, 1787. It's believed to form part of the stellar association Cassiopeia OB8, which also contains M103, NGC 654, NGC 659 and some supergiant stars scattered between them. NGC 663 is interesting to professional astronomers as it also contains a high number of Be stars and some blue stragglers.

NGC 663 Finder Chart - (credit:- freestarcharts)

NGC 663 Finder Chart - pdf format (credit:- freestarcharts)

NGC 663 Data Table

NGC663
Caldwell10
Object TypeOpen Cluster
ConstellationCassiopeia
Distance (light-years)7,000
Apparent Mag.7.1
RA (J2000)01h 46m 16s
DEC (J2000)61d 13m 06s
Apparent Size (arc mins)16 x 16
Radius (light-years)16.5
Age (years)20 Million
Number of Stars>80
Other NameCollinder 20


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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