M93, mag. +6.0, is a bright large open cluster of about 80 stars located in the southern constellation of Puppis. It has an apparent diameter of 22 arc minutes, which is equivalent to about 2/3rds the apparent diameter of the full Moon. Under dark skies, M93 is visible to the naked eye appearing as a misty patch of light. This cluster is an easy binocular object and a wonderful sight in small telescopes where the brightest members form a distinct central triangle. It was one of the last deep sky objects discovered by Charles Messier, which he catalogued on March 20, 1781.

Finding M93 is not difficult. It's positioned in western Puppis a few degrees from the Canis Major border and not far from Sirius (α CMa), the brightest star in the night sky. Sirius can be found by connecting the three bright stars of Orion's belt and extending the line southwards. Positioned 8 degrees southeast of Sirius are Omicron1 CMa (ο1 CMa - mag. +3.9) and Omicron2 CMa (ο2 CMa - mag. +3.0). To locate M93, imagine a line connecting these two stars and then extend it eastwards and slightly southwards for about 10 degrees to reach the cluster.

It's best seen from southern latitudes during the months of December, January and February.

M93 Open Cluster (credit:- David Malin/Australian Astronomical Obs.)

Finder Chart for M93 (credit:- freestarcharts)

Finder Chart for M93 - pdf format (credit:- freestarcharts)

A pair of 7x50 or 10x50 binoculars easily shows M93 with the brightest members resolved. At medium magnifications through small scopes it appears large and quite compact. Towards the centre is an arrowhead or wedge shaped grouping of bright stars. With averted vision the nebulous background resolves into many fainter stars. Larger reflectors of aperture 200mm (8-inch) or greater, reveal dozens of mostly blue giants but also some red giants, which add to the charm of this dazzling cluster.

M93 is 3,600 light-years distant and has a spatial diameter of 20 light-years. It's estimated to be about 100 million years old.

M93 Data Table

Messier93
NGC2447
Object TypeOpen Cluster
ConstellationPuppis
Distance (light-years)3,600
Apparent Mag.+6.0
RA (J2000)07h 44m 29s
DEC (J2000)-23d 51m 11s
Apparent Size (arc mins)22 x 22
Radius (light-years)10
Age (years)100 Million
Number of Stars80
Other NameCollinder 160

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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