|IC 5146 "Cocoon Nebula": Emission Nebula (Cygnus) RA: 20h 34.1m / DEC: +45° 38'.7|
Instrument: 18-inch Obsession
The Cocoon Nebula looks impressive in long exposure photos and CCD images, but make no mistake; this is a difficult visual target. It requires a very dark sky just to be seen in any aperture. In fact, the far more impressive visual subject in this neck of the celestial wood is sinewy Barnard 168 (B168), a slender dark nebula that snakes its way west from the Cocoon like some inky river in the night. But that's another observation. The sketch at left captures the Cocoon Nebula's (IC 5146) appearance at 109X in the big Dob. My sketch combines two views. The first is unfiltered through my 22mm Nagler Type 4. The nebulosity is smooth and rangy, seemingly filling most of the field. The second is through the same eyepiece fitted with a UHC filter. The nebulosity is better defined, an obvious dark lane bisecting the central brightest portion of the nebula into eastern and western halves. You'll see this galactic cloud centered, enmeshed with a grouping of six stars. The two brightest of these shine at 9.7 magnitude. This central nebulous patch is roughly 7'x6' in dimension in the 18-inch. More than 60 stars from the cluttered field are included in my drawing. Of particular note, is the string of stars poised just inside the northeast field edge. You'll find the Cocoon Nebula about 12.5° east of naked eye Deneb in Cygnus.
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Revised: November 7, 2005 [WDF]