Sh2-119
HII Region in Cygnus
About
The Clamshell Nebula, an emission nebula in Cygnus about 2,200 light-years away and roughly 3° across. Two halves of glowing gas sit either side of the blue giant 68 Cygni, which lights them. Bok globules and lanes of dust are scattered across it.
Imaging tips
- The nebula spans about 3°, so it needs a wide lens or a small refractor, or a mosaic.
- An emission nebula, so narrowband suits it. One imager took 10 hours each of Hα and OIII in 600 s subs, plus short RGB for stars, 21 hours 30 minutes in all.
- That imager's 550 mm frame had a 4.37° field and included the open cluster NGC 7044 and 68 Cygni.
- Best in July and August; it passes almost overhead, about 84° altitude from 50°N.
Facts
- Size
- 120′
- Magnitude
- —
- Coordinates
- RA 21h 18.5m, Dec +43° 56′
- Framing, APS-C
- 200–340 mm
- Framing, full frame
- 310–520 mm
- Best months
- Jul, Aug
- Peak altitude
- 84° from 50°N, 81° from 35°N