Capturing the Majestic Andromeda Galaxy: A Beginner's Journey and Processing Puzzle

It's always thrilling to see the cosmos through the lens of a telescope, and for many astrophotographers, the Andromeda Galaxy (M31) is a prime target. This post features an image of M31 captured by a budding enthusiast, along with a candid discussion about the challenges faced during processing. If you're new to the hobby or looking to refine your skills, there are valuable lessons to be learned here!

The Setup:

• Telescope: Askar 71f (6.9f)
• Camera: Canon EOS 600D (unmodified)
• Integration: 180 x 30s (1h 30m total)
• Conditions: Bortle 4, full moon night (99% illumination)
• Calibration Frames: 25 darks, 54 flats, 49 biases

The Image:

Processing Challenges and Community Advice:

The astrophotographer utilized Siril for stacking and initial processing, including background extraction, spectrometric color calibration, photometric color calibration, and stretching. GIMP was used for minor adjustments like saturation and hue saturation. However, the resulting image presented some puzzling color issues, notably a reddish tone across the majority of the frame, with two distinct columns on the left and right appearing different. This same effect was observed in images of the Pleiades.

The question arose: are these issues due to insufficient calibration frames or incorrect processing techniques?

The community offered some insightful suggestions:

• Gradient Reduction: The use of software like GraXpert was recommended to help address gradients, which can often be caused by light pollution or even the moon.
• Data Acquisition Under Moonlit Skies: It was noted that imaging under a full moon is a challenging endeavor, highlighting the bravery of the photographer in attempting this under such conditions. However, the image was still considered good for the circumstances.
• Stretching and Denoising: Advice was given to experiment with further stretching the data to reveal more details. Tools like StarNet (used in the final image for star reduction) and other free denoising software were suggested to improve the overall quality without blowing out stars.
• Potential Causes for Gradients: Beyond light pollution and the moon, tilt in the optical train or the use of filters (though none were used in this case) were mentioned as other potential sources of gradients.

Lessons Learned:

This experience underscores the learning curve in astrophotography, especially when dealing with less-than-ideal conditions like a full moon. The photographer's willingness to share their challenges and accept feedback is commendable and a great resource for others starting out.

Key takeaways include the importance of:

• Understanding the impact of light pollution and lunar illumination on image processing.
• Exploring various software tools for gradient reduction, stretching, and denoising.
• Experimenting with calibration frames to ensure optimal data capture.

Keep capturing, keep learning, and keep sharing your celestial journeys!