SH2-105 (also known as NGC 6888 or Crescent Nebula) is an emission nebula in constellation Cygnus which ionized by the Wolf-Rayet star WR 136 which lies in a distance of about 5600 ly from earth (according to GAIA DR3).
That kind of stars are supernova progenitors. At least a part of the gas was ejected when the star became a red giant. The apparent diameter of this nebula is about 17' (arcminutes).
0.67° × 0.51° (full view)
400mm Newton at f=1520mm
North is up (approximately)
0.8 arcsec/pixel (at full resolution)
Total exposure times:
All image processing steps are deterministic, i.e. there was no manual retouching or any other kind of non-reproducible adjustment. The software which was used can be downloaded here.
Image processing steps where:
Bias correction, photon counting
Dark current subtraction, flatfield correction, noise estimation
Alignment and brightness calibration using stars from reference image
Stacking with masking unlikely values and background correction
Extracting stars from the emission line images using information from continuum images
Denoising and deconvolution both components (stars and residual)
Dynamic range compression using non-linear high-pass filter