NGC 7023 (Iris Nebula) and Molecular Clouds in Cepheus
Images below show a dusty 6.25° × 4.0° large region in Cepheus containing NGC 7023 (Iris Nebula) and VdB 4141 (Ghost Nebula).
First figure shows a color composite from SDSS I' (mapped to red), R' (mapped green) and G' (mapped blue) filters.
The difference between the color channel is also visualized in the following figure where the color components from the image above can be compared interactively.
The following pictures are an attempt to compare the results from the SDSS filters with RGB shots.
||6.25° × 4.0°
||12/2021 to 01/2022
||2-3 × Nikon 300mm f/2.8 AF-S
||2-3 × QHY600L
||North is up (exactly)
||3 arcsec/pixel (at full resolution)
|Total exposure times:
|SDSS G':|| 10.5 h
|SDSS R':|| 9.9 h
|SDSS I':|| 6.1 h
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, dark current subtraction, flatfield correction, noise estimation
- Alignment and brightness calibration using stars from reference image
- Stacking with masking unlikely values and background correction
- Star subtraction
- Denoising and deconvolution
- Color composition
- Dynamic range compression using non-linear high-pass filter
- Tonal curve correction