Capturing the North America Nebula: A Bortle 4/5 Journey
This past July 18th, I ventured out to capture the breathtaking North America Nebula from Burlington, VT. Under Bortle 4/5 skies, I aimed to push my equipment and processing skills further than ever before. This image represents my first attempt with over an hour of total exposure time, and while I'm still refining certain aspects, the progress is undeniable.
The Celestial Canvas: The North America Nebula
The North America Nebula (NGC 7000) is an emission nebula in the constellation Cygnus. Its distinctive shape, resembling the continent of North America, makes it a popular target for astrophotographers. It's a vast region of ionized hydrogen gas, illuminated by the nearby bright star Deneb.
Gear Used:
To bring this celestial wonder to life, I employed a robust setup:
- Scope: Apertura 90mm Triplet with a 1x Flattener
- Mount: Skywatcher EQ6-R for stable tracking
- Camera: ZWO ASI2600MC-Pro for high-quality color data
- Guide Scope: Svbony 60mm
- Guide Camera: ZWO ASI120MM for precise guiding
- Focuser: ZWO EAF for automated focusing
- Filter: Optolong L-eNhance for capturing narrowband signals in a broadband camera
Acquisition Details:
My goal was to gather significant data for a richer image:
- Total Exposure Time: 72 frames x 180 seconds = 1.67 hours
- Gain: 100
- Camera Temperature: -10°C
All imaging was conducted using NINA for control and PHD2 Guiding for precise autoguiding.
Processing Pipeline:
Achieving the desired result involves a meticulous processing workflow:
- Siril OSC Pre-Processing: Initial calibration and stacking of the light frames.
- GraXpert Background Extraction: Smoothing out and removing gradients from the image.
- Siril for SPCC, Starnet, Stretch, Recombination:
- SPCC (Supercharged Photometric Color Calibration): For accurate color balance.
- Starnet: To remove stars and allow for detailed nebula processing.
- Stretch: Non-linear stretching to reveal faint details.
- Recombination: Merging the starless image with processed stars.
Reflections and Next Steps:
I'm proud of the increased exposure time and the overall improvement in detail compared to my previous attempts. However, I'm not entirely satisfied with the intense dark blues in the top middle-left portion of the image. This is a common challenge with deep-sky processing, and I'm always eager to learn and refine my techniques.
I'm particularly looking for suggestions on how to better handle these color casts and enhance the overall aesthetic of the image. Any advice on further processing steps or alternative approaches would be greatly appreciated by the community!
