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

Object TypeGlobular Cluster
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 - September 2017

Neptune reaches opposition on September 5th

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for September

Northern Hemisphere
West:- Jupiter (mag. -1.7)
Southwest:- Saturn (mag. +0.5)
East:- Neptune (mag. +7.8)
South:- Neptune
East:- Uranus (mag. +5.7)
West:- Neptune
South:- Uranus
East:- Venus (mag. -3.9), Mars (mag. +1.8) (from second week), Mercury (mag. +0.5 to -1.3) (from second week)

Southern Hemisphere
West:- Jupiter
Northwest:- Saturn
East:- Neptune
West:- Saturn
North:- Neptune
Northeast:- Uranus
West:- Neptune
Northwest:- Uranus
Northeast:- Venus
East:- Mars (end of month)

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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