NGC 6888 : A fresh croissant from the oven
NGC 6888 (Caldwell 27 or Sharpless 105 or Crescent Nebula) is an emission nebula located in the constellation Cygnus.
NGC 6888 was discovered in 1792 by the German-British astronomer William Herschel.
This nebula was born from the rapid stellar winds of the star HD 192163 (WR 136).
This massive star will likely explode as a supernova in about 100,000 years. The nebula and its star have been the subject of numerous publications.
Perhaps the most precise distance comes from the parallax measurement of WR 136, the star that spawned the nebula. This measurement was made by the Gaia satellite.
The star HD 192163 (WR 136) began what would be the end of its life by exploding as a supernova, just 4.5 million years after its birth. It first expanded enormously to become a red giant and ejected its outer layers at speeds of about 20,000 mph (32,000 km/h).
Set up
Fra400 on AZ EQ6 GT mount
ASI533 MC Pro camera for imaging
ASI120 mini for guiding via OAG Zwo (Off-Axis-Guider)
Antlia Duo Band 5 nm
Control via ASIAIR PLUS
The session
NGC6888 was taken last year in December 2024 in La Palma (Spain)
28 frames, 600” each
Total integration : 4 hours 40’
Processing
Calibration, Alignment and Stacking with Siril
Processing with Pixinsight
Procedure via PixInsight :
Dynamic Crop
Gradient correction
Image Solver
SPCC
BlurX Terminator (Correct only)
NoiseX Terminator
StarX Terminator to remove the stars
Stars Strech via SetiAstro
Starless image stretched with EZ Suite
SCNR to remove the green noise on both images
Luminance extraction on the starless
Light Saturation on the starless
Masks & curve transformation on the starless
HDR Multiscale Transform to recover details (scale 6)
Pixel Math to bring the stars back
Noise reduction via NoiseX (Just a hair)
Clear Sky !
NGC 6888 Crop
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