NGC 457 is the brightest open cluster in Cassiopeia and one of the finest objects of its type in the northern sky. At magnitude +6.4, it's just beyond naked-eye visibility but easily seen with binoculars and a beautiful sight through telescopes. The brightest cluster stars are arranged in prominent lines and curves lines appearing to resemble an Owl shape, hence the popular name "the Owl Cluster". It's located 7,900 light-years distant.

NGC 457 was discovered by William Herschel in 1787. Finding the Owl Cluster is easy; it's positioned two degrees south-southeast of eclipsing binary star system Ruchbah (δ Cas - mag. +2.7). This star is one component of the characteristic "W" asterism of Cassiopeia. The brightest star inside NGC 457 is Phi Cas (φ Cas - mag. +5.0). Despite not being a member of the cluster, this foreground star is visible to the naked eye. Together with another non-cluster star - seventh magnitude HD 7902 (HIP 6229) - they form the bright eyes of the Owl greatly adding to the splendour of the view through backyard scopes.

NGC 457 is best seen from Northern Hemisphere latitudes during August, September and October. It appears high in the sky and even overhead from many locations. From latitudes greater than 32N, the Owl is circumpolar and never sets.

NGC 457 -NGC 457 - Owl Cluster (Henryk Kowalewski)

Finder Chart for NGC 457 - Owl Cluster

Finder Chart for NGC 457 - Owl Cluster - pdf format

Through 7x50 or 10x50 binoculars the two brightest stars form a lovely double star separated by 135 arc seconds. With averted vision especially on nights of good seeing the brightest cluster stars hint at resolution against a hazy backdrop. A small 80mm (3.1-inch) scope reveals a fine cluster consisting of two dozen mostly white stars with the brightest two yellow and blue in colour. A group of 9th and 10th magnitude stars in a rectangular shape forms the body of the Owl with arms extending outwards in a north-south direction. Medium sized 200mm (8-inch) scopes reveal a stunning sight with up to 100 stars visible across 20 arc minutes of apparent sky. Easily seen is the clusters brightest member, a magnitude +8.4 deep orange ruddy coloured supergiant star.

Since not included in Messier catalogue, NGC 457 is often overlooked and not as well known as other bright clusters. However, this beautiful group of stars is one of the best open clusters in the northern sky. It has an estimated age of 21 million years and is number 13 in the Caldwell catalogue.

NGC 457 Data Table

Caldwell13
NGC457
NameOwl Cluster
Object TypeOpen Cluster
ConstellationCassiopeia
Distance (light-years)7,900
Apparent Mag.+6.4
RA (J2000)01h 19m 33s
DEC (J2000)58h 17m 27s
Apparent Size (arc mins)20 x 20
Radius (light-years)23
Age (years)21 Million
Number of Stars>150
Other Name (s)ET Cluster, Collinder 12, Melotte 7

Sky Highlights - May 2017

Mercury
Mercury reaches greatest elongation west on May 17, 2017

Meteor Shower
Eta Aquariids meteor shower peaks on May 5th and 6th, 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for May 2017

Northern Hemisphere
Evening
West:- Mars (mag. +1.6)
South:- Jupiter (mag. -2.4)
Midnight
Southwest:- Jupiter
Southeast:- Saturn (mag. +0.2)
Morning
South:- Saturn
East:- Venus (mag. -4.7)

Southern Hemisphere
Evening
West:- Mars
North:- Jupiter
Midnight
Northwest:- Jupiter
North:- Saturn
Morning
Northwest:- Saturn
East:- Venus, Mercury (mag. +2.5 to -0.3), Neptune (mag. +7.9)

Deep Sky
Naked eye / binoculars:-
Melotte 111 - Mel 111 - The Coma Star Cluster (Open Cluster)
Messier 44 - M44 - The Praesepe (Open Cluster)

Telescopes:-
Messier 67 - M67 - Open Cluster
Messier 51 - M51 - The Whirlpool Galaxy (Spiral Galaxy)
Messier 97 - M97 - The Owl Nebula (Planetary Nebula)
Messier 101 - M101 - The Pinwheel Galaxy (Spiral Galaxy)
Messier 65 – M65 – Spiral Galaxy
Messier 66 - M66 - Intermediate Spiral Galaxy
Messier 95 - M95 - Barred Spiral Galaxy
Messier 96 - M96 - Intermediate Spiral Galaxy
NGC 4244 - Spiral Galaxy
NGC 4565 - Needle Galaxy - Spiral Galaxy

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