My First Astroshot: Troubleshooting a Bright Center and Corners
Hello fellow stargazers!
As a budding astrophotographer, I recently took my first crack at capturing the wonders of the night sky. I'm eager to share my maiden voyage, but I've run into a curious issue with the final stacked image and would love your expert advice.
My Setup:
- Telescope: C14
- Focal reducer: 0.7x
- Autoguiding: PHD2 with ASI 294MM Pro
- Camera: Canon EOS RA
- Calibration frames: 25 Bias, 25 Darks, 25 Flats
- Light frames: 40 × 30 seconds
I utilized DeepSkyStacker for processing, diligently discarding any light frames scoring below 700, with my best frame achieving a respectable 1433.
The Mystery Bright Spots:
Upon stacking, I noticed a prominent, almost lightning-ball-like glowing spot right in the center of my image. Furthermore, the corners appear unusually bright. This wasn't quite the pristine deep-sky image I was hoping for!
Seeking Your Insights:
Does anyone have an idea what might be causing this phenomenon? I'm particularly curious about the bright center and the elevated brightness in the corners. Any thoughts or troubleshooting tips would be greatly appreciated!
Potential Causes Discussed:
From the community, a few possibilities have emerged:
- Background Gradient: This could be addressed with background extraction tools. Programs like Graxpert, with its AI-based background extraction, are often recommended.
- Flats and Vignetting: Focal reducers are known to cause or amplify vignetting. While flats are meant to correct this, incorrect flats could still leave issues. Testing the stack without flats might reveal if they are the culprit, and a dark ring pattern often points to vignetting.
I'm eager to dive deeper into these suggestions and refine my technique. Thanks for your help!
