Pixinsight/ASI2600: Decoding Those Pesky Imaging Artifacts

Welp, new equipment apparently means new problems. My recent foray into astrophotography with a new Celestron Edge 8" scope and an ASI2600mc Air camera, paired with a 0.7x reducer, has revealed some unwelcome guests in my images: those characteristic circular artifacts.

The Mystery of the Rings

These spots and rings, some appearing like shadows and others like inverse bright spots, have been proving stubbornly resistant to standard gradient removal and noise reduction techniques. While stretching and aggressive contrast adjustments can make them blend away, it's significantly disrupting my usual workflow and isn't a sustainable solution.

Troubleshooting Steps Taken

I've been diligently cleaning all accessible glass surfaces, including the scope's front plate, rear lenses, and both sides of the reducer. I even cleaned the camera sensor. Despite these efforts, the artifacts persist.

My current imaging train setup:

• Scope: 8” Celestron Edge
• Camera: ASI2600mc Air
• Reducer: 0.7x

I'm eagerly awaiting some M54 spacer tubes which will allow me to remove the reducer from the equation. This will be a crucial step in isolating whether the reducer is the source of the problem.

Expert Advice: The Power of Flat Frames

After sharing my predicament, the overwhelming consensus pointed towards a critical missing piece in my calibration routine: flat frames. While I had collected darks, bias frames, and even some flat frames, it seems my understanding and execution of flat framing might have been where the issue lay.

Key takeaways from the community:

• Take Flat Frames: This is the most common solution for dust motes and other optical artifacts. They are essential for correcting these issues.
• Frequency of Flats: Flats should ideally be taken for each imaging session or any time the optical train is altered. This is because dust can settle or shift between sessions.
• Flat Frame Exposure: Flats should be exposed to reach approximately 30,000 ADU, which typically means exposures of less than a second, depending on your focal ratio and filters.
• Flat Frame Consistency: Ensure your flat frames are taken with the exact same optical train, filters, and camera orientation as your light frames.
• Dark Library: Creating a dark library is beneficial, especially if camera temperature and exposure times remain consistent.

Moving Forward

I'll be focusing on implementing a robust flat framing routine, ensuring I capture them correctly and frequently. The insights from fellow astrophotographers have been invaluable, and I'm optimistic that with the proper application of flat frames, these troublesome artifacts will soon be a distant memory.

Has anyone else encountered similar issues with the ASI2600 or similar equipment? Share your experiences and tips in the comments below!