13 Jul 2021
NGC 6888: The Crescent Nebula (HOO)
About 4,700 light years away, NGC 6888 is formed by a fast stellar wind from the Wolf-Rayet star HD 192163, also known as WR 136. The star is shedding its outer envelope, ejecting the equivalent of the Sun's mass every 10,000 years. This stellar wind is colliding with, and energizing, a slower-moving wind ejected by the star when it became a red giant around 400,000 years ago. The result of the collision is a shell about 25 light-years across. Two shock waves, one moving outward and one moving inward, heats the stellar wind to X-ray-emitting temperatures. The central star WR 136 will probably undergo a supernova explosion sometime in the next million years.
source: skysafari
RA: 20h 12m 13.3s
DEC: +38° 20’ 22.9"
Size: 21.1 x 21.2 arcmin
Orientation: Up is 0.121 degrees E of N
Location: Cygnus
Distance: 5 kly
Magnitude: 7.4
Acquisition August 2020
Total acquisition time of 3.3 hours.
Location: IC Astronomy Observatory, Spain
Ha: 20 x 300s
OIII: 20 x 300s
Optics: Officina Stellare ProRC 700
Mount: Officina Stellare equatorial fork mount
CCD: FLI PL 16803
Pre Processing: CCDstack, Pixinsight & Excalibrator
Post Processing: Photoshop CC
NGC 6888
2 credit
- Type of target............................................................................................................................Emission Nebula
- Camera............................................................................................................................FLI PL16803
- Target coordinates............................................................................................................................RA 303.0292 Dec 38.35
- Hemisphere............................................................................................................................Northern
- Telescope location............................................................................................................................Spain
- Transient event............................................................................................................................No
- Observed on............................................................................................................................16 Jul 2020 - 14 Dec 2021
Filter | Avg Exp (s) | Total Exposure | Subframes |
|---|---|---|---|
| Halpha | 930 | 2h35m | 10 |
| Luminance | 42 | 7m | 10 |
| Red | 12 | 2m | 10 |
| Green | 27 | 4m | 9 |
| Blue | 13 | 2m | 9 |