NGC 6934, also known as Caldwell 47, is a 9th magnitude globular cluster located in Delphinus. Backyard scopes show a fuzzy disk of nebulosity, about 5 arc minutes in diameter with a brighter core. The globular is not visually spectacular, but that's due to distance and not intrinsic brightness. At 50,000 light-years, it's one of the more remote globulars easily seen with amateur scopes.

William Herschel discovered NGC 6394 on September 24, 1785. He classified it as a "bright nebula" but wasn't able to resolve any stars.

The cluster is best seen during the months of July, August and September. It has a spatial diameter of 120 light-years and is estimated to contain about 250,000 stars. It's believed to be around 10 billion years old.

NGC 6934 (credit:- NASA, ESA, and The Hubble Heritage Team (STScI/AURA))

Finder Chart for NGC 6934 (credit:- freestarcharts)

Finder Chart for NGC 6934 - pdf format (credit:- freestarcharts)

NGC 6934 is located 4 degrees south of Epsilon Delphini (mag. +4.0) and 1 degree northwest of a pair of 6th and 7th magnitude stars. The globular is a difficult binocular object, ideally requiring dark skies. A small 80mm (3.1-inch) refractor shows a faint, clearly non-stellar circular patch of light. Just to the west of the cluster is a 9th mag. star.

NGC 6934 can be partially resolved with a 300mm (12-inch) telescope. At about 200x magnification dozens of stars are revealed, especially on nights of good seeing. The cluster appears compressed and grainy. A very large 450mm (18-inch) scope at high powers will resolve some of the stars at the core. Photographically, NGC 6934 spans some 8.4 arc minutes across but visually it appears a few arc minutes less.

In Delphinus there is an even more distant globular, NGC 7006. It's located about 10 degrees to the northeast of NGC 6934 and at 135,000 light-years, is nearly three times further away.

NGC 6934 Data Table

NGC6934
Caldwell47
Object TypeGlobular Cluster
ConstellationDelphinus
Distance (light-years)50,000
Apparent Mag.+8.9
RA (J2000)20h 34m 11s
DEC (J2000)+07d 24m 16s
Apparent Size (arc mins)8.4
Radius (light-years)60
Age (years)10 Billion
Number of Stars250,000

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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