C19 — Cocoon Nebula
Emission Nebula in Cygnus
About
IC 5146, a star-forming cloud in Cygnus that is partly glowing hydrogen, partly reflected starlight and partly dark dust. Sources give its distance as roughly 2,500 to 4,000 light-years. A dark lane, Barnard 168, trails westward from it like a tail.
Imaging tips
- At 2,420–4,040 mm on APS-C the nebula alone spans a third to half of the frame; AstroBackyard shows that a 430 mm frame takes in the dark dust tail.
- It mixes emission, reflection and dark nebulosity: broadband colour works, and Galactic Hunter added hydrogen-alpha data to an LRGB set.
- Single frames look poor; stacking many of them makes a large difference, and Galactic Hunter reached 52 hours in total for one image.
- B168 lies about 3′ away, so its dust is in the same field; the wider tail needs a wider lens.
- Best in August and September; it passes almost overhead (about 87°) from 50°N.
Facts
- Size
- 10′
- Magnitude
- 7.2
- Coordinates
- RA 21h 53.6m, Dec +47° 16′
- Framing, APS-C
- 2420–4040 mm
- Framing, full frame
- 3710–6190 mm
- Best months
- Aug, Sep
- Peak altitude
- 87° from 50°N, 78° from 35°N
Nearby
- B168 · 3.1′ away