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NGC 40
Planetary Nebula
NGC 40, PNG 120.0+09.8, PK 120+09.1, ARO 1
Integrated Visual Magnitude: 10.7
Apparent Diameter: 1.6'
Magnitude of central star: 11.6
Distance: 3,700 ly
Actual Diameter: 1.7 ly

Minimum requirements to view: 6-inch scope and dark skies


This planetary is one of the gems of Autumn in larger telescopes, although it is visible in smaller scopes as a round haze. The relatively bright central star is an easy target for six inch or larger telescopes.

In my six inch, NGC 40 was easily found tucked away between two 10th magnitude stars. It was obvious even at 50x. The central star was easily visible. At higher magnification, this planetary was a bit of a disappointment as I was not able to see any hint of structure or color.


A six-inch view at 150x. North is down and east is right.

Long exposure photographs such as the one above show asymmetry. Some of this detail is visible in larger instruments, which reveal knots in the outer ring and a "Z" shaped structure in the disk.  McNeil describes it as "an irregular disk with traces of ring structure plus an irregular disk and a fainter spherical envelope." North is down and east is right.

The central star of this nebula presents a bit of a puzzle. It is hot enough to excite the nebula to a higher state than that observed. This can be explained as the result of shielding material near the star. 
 

Millennium Star Atlas Vol I Chart 24
Sky Atlas 2000 Chart 1
Uranometria 2000 Vol I Chart 3