IC 5146 (Cocoon Nebula), Barnard 168 (Black Cigar) & Collinder 470 (Open Cluster)
A Lit Celestial Cigar
Embedded deep in the milky way stream at the far eastern end of the Swan where it meets the
Lizard resides the Cocoon Nebula (IC 5146) and the Black Cigar (Barnard 168). Tightly bound
to and providing energy to the nebula is the open cluster Collinder 470.
It has always been confusing to me that this area of the sky is often marked in beginning field
guides showing only the Cocoon Nebula without mentioning the open cluster or even, on occasion,
the Black Cigar (a dark nebula). This makes no sense to me since the Cocoon is the most difficult
of the three deep sky objects to observe.
From Alpha Ridge Park on August 29, 2019 under a reasonably good sky, the Black Cigar was
an easy target in my 7x42 binoculars. The elongated black “hole” in the milky way, several times
longer than the full moon was evident against the star-studded milky way.
In the 110mm refractor, used in the drawing, the Black Cigar was too magnified to make out well,
but the weak-appearing open cluster at its eastern end with its two brightest (9.5 magnitude)
members was conspicuous. One of these stars (BD+463474) is the chief source of energy for
the Cocoon Nebula. But the Cocoon Nebula proper remained invisible in the small refractor.
A Hydrogen-beta nebula filter was the trick in seeing the Cocoon Emission Nebula. Even then, it
took a little effort to tease out. When viewed in large telescopes, the Cocoon Nebula has several
dark lanes running through it that somewhat resembles the Trifid Nebula (M20). But the little
refractor could only make out a shapeless faint glow. I will still take the observation as a win for
the night.
The Black Cigar is outlined in my drawing in order to make it more obvious. The dark nebula
continues out of the field-of-view of the drawing at one end and wraps around the Cocoon
Nebula at the other end. Remember that in Diagonal View the orientation is mirror reversed.
Lizard resides the Cocoon Nebula (IC 5146) and the Black Cigar (Barnard 168). Tightly bound
to and providing energy to the nebula is the open cluster Collinder 470.
It has always been confusing to me that this area of the sky is often marked in beginning field
guides showing only the Cocoon Nebula without mentioning the open cluster or even, on occasion,
the Black Cigar (a dark nebula). This makes no sense to me since the Cocoon is the most difficult
of the three deep sky objects to observe.
From Alpha Ridge Park on August 29, 2019 under a reasonably good sky, the Black Cigar was
an easy target in my 7x42 binoculars. The elongated black “hole” in the milky way, several times
longer than the full moon was evident against the star-studded milky way.
In the 110mm refractor, used in the drawing, the Black Cigar was too magnified to make out well,
but the weak-appearing open cluster at its eastern end with its two brightest (9.5 magnitude)
members was conspicuous. One of these stars (BD+463474) is the chief source of energy for
the Cocoon Nebula. But the Cocoon Nebula proper remained invisible in the small refractor.
A Hydrogen-beta nebula filter was the trick in seeing the Cocoon Emission Nebula. Even then, it
took a little effort to tease out. When viewed in large telescopes, the Cocoon Nebula has several
dark lanes running through it that somewhat resembles the Trifid Nebula (M20). But the little
refractor could only make out a shapeless faint glow. I will still take the observation as a win for
the night.
The Black Cigar is outlined in my drawing in order to make it more obvious. The dark nebula
continues out of the field-of-view of the drawing at one end and wraps around the Cocoon
Nebula at the other end. Remember that in Diagonal View the orientation is mirror reversed.