The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus. The designation NGC 7023 refers to the open cluster within the larger reflection nebula designated LBN 487.
Image:
Equipment:
- Nikon D90
- Sigma 300mm F.28
- Sky-Watcher Star Adventurer
- Star Adventurer tripod
- DIY lens hood with 2 violin strings for diffraction spikes
- Bahintov Mask
- Intervalometer
Acquisition:
- Lens stopped down to F4.0, Iso 1600, 2 minute exposures
- 198 x 2′ light frames
- 200 bias
- 50 flats
- 5 darks
- Taken from a Bortle 2 zone
- Taken across two nights: 5/1/2021, 5/2/2021
Processing:
- Manually stacked in Pixinsight
- DBE
- Color calibration
- John Rista Denoise
- Masked strech
- Starnet++
- Touched up starless version in photoshop
- Extracted Luminance and reapplied in Pixinsight
- Curves Transformation
- HDR Multiscale Transform
- Local Histogram Equalization
- A bit more curves
Annotated image:
