Witch's Broomstick Nebula: A Celestial Struggle in Los Angeles
Astrophotography, even with its breathtaking results, often involves overcoming significant hurdles. Today, we're looking at a capture of the enigmatic Witch's Broomstick Nebula (also known as IC 2118) that exemplifies this. The image, shared by /u/Particular_Limit_, showcases the beauty of this celestial object, but it's the story behind the capture that truly stands out.
The Setup and the Struggle
This image was acquired using a rather unconventional setup, especially for deep-sky astrophotography: a 305 mm Reflector telescope. While a large aperture offers great light-gathering potential, reflectors can be prone to collimation issues, and in this case, a "cheap Crawford focuser that shifts with different weights" presented a significant challenge. Compounding this, the capture took place in Los Angeles, a Bortle 9 location, meaning extreme light pollution. Despite these difficulties, the photographer pushed forward.
The equipment list includes:
- Telescope: 305 mm Reflector
- Camera: ZWO ASI533MC (-10 C) + L-eNhance Dual Narrowband Filter
- Guide Scope: 50 mm Starboosa guidescope
- Guide Camera: ZWO ASI120MM
- Mount: ZWO AM5
- Accessory: ASIAIR Plus
Acquisition Details
- Date: August 30, 2025 (AM)
- Location: Los Angeles (Bortle 9)
- Exposure: 600s (per sub)
- Subs: 5
- Gain: 200
Processing Workflow (Pixinsight)
The post-processing was carried out in Pixinsight, a powerful tool for astrophotography image manipulation. The workflow involved:
- Background removal
- Spectrophotometric calibration
- BlurXTerminator
- Noise reduction
- Histogram stretch
- Star removal
- Narrowband Normalization
- Curves transformation
- Star recombination
- Curves transformation (again)
A Testament to Persistence
The photographer acknowledges the "bad collimation" and the "shifting focuser" but chose to share the result anyway, a decision met with encouragement from the community. Suggestions for improvement included exploring shorter exposures to mitigate the effects of optical aberrations and focusing on acquiring more frames for better noise reduction. The advice also touched upon preserving star colors and avoiding aggressive background clipping. One particular suggestion was to capture some data without the L-enhance filter to blend in RGB stars for a more natural look.
This image serves as a reminder that the pursuit of astrophotography is often a journey of problem-solving and persistence, with dedication sometimes yielding remarkable results even under challenging conditions.
