Nightscapes & Deep Sky Colors

Astrophotography Brian A. Morganti

Cocoon Nebula Sh2-125

with Open Cluster IC 5146 & Dark Nebula B168





The Cocoon Nebula, which includes both emission and reflection nebulosity, is a stellar nursery with its delicate fabric of glowing hydrogen torn asunder by the solar wind of newborn stars.  Beyond the glow of the hydrogen, the surrounding interstellar dust begins to dominate.  At the edge of the red emission nebula, this dust reflects pale blue light from nearby stars.  Farther away, the dust fades, and instead blocks the light of the background stars.  The nebula is about 12 arc-minutes across, but in actual size is about 15 light-years across.

The star cluster IC 5146 is sparse and only contains about 20 stars, the brightest of which is about magnitude 9.6 near the center of the cluster and nebula.  This cluster is about 4000 light-years away.

The dark nebula  B168 (Barnard) is visible in binoculars and is rather interesting amidst the rich star fields in Cygnus.  This dark nebula surrounds the cluster-nebula and then extends westward forming the appearance of a trail behind the Cocoon.


  • Date & Location:  November 25, 2011 - Bernville, PA

  • Weather:  Calm wind, Temperature Start - 45F / End - 33F

  • Sky Conditions:  Clear with average transparency, but some high clouds near end.

  • SQM-L: Average Start 20.09 / Stop 20:30

  • Optics:  TeleVue NP101is Refractor with 0.8x reducer 432mm @ f4.3

  • Filter:  Astronomic  EOS clip-in CLS-CCD (Light Pollution Suppression)

  • Mount:  AstroPhysics AP900GTO

  • Guiding:  None - PEM active

  • Camera:  Canon T1i (500D) Hap Griffin Modified - Baader UV/IR

  • Exposure:  42 x 5min @ ISO800 total 210 minutes (3hrs - 30min)

  • Calibration Frames:  16 Dark / 16 Bias

  • Processing:  Images Plus 3.82, PS CS4, Noise Ninja, GradientXTerminator, NIK 

  • Comments:  Should have refocused more frequently because of large temperature least once an hour rather than after 2 hours.  Final images began to show some star bloating.



Astrophotography  -  Nightscapes & Deep Sky Colors