July 2025 Stargazing: Supernova 2025rbs in NGC 7331, Learning Siril and Graxpert

This is a challenging month for stargazing, it’s been raining most nights. Luckily during the final three nights of July we had brief clear patches, but fast-moving clouds limited us to targeting areas with the best sky conditions.

Our primary target was Supernova 2025rbs in NGC 7331! Here’s the list of deep-sky objects (DSOs) we successfully imaged:

• NGC 7293, Helix Nebula
• NGC 7023, Iris Nebula
• IC 1396, Mu Cephei
• Saturn

Learning Siril and Graxpert

Another significant challenge in this hobby is operating under Bortle 7 skies. While I appreciate the stacked images from the Seestar S30, I knew the data could be stretched further with proper processing.

I’ve been learning Siril and Graxpert and the more I process images, the more I am understanding what I am doing, lol.

My priority is extracting maximum detail from the data rather than focusing solely on aesthetics.

Here’s the Iris Nebula: 79 subs x 20s

Here’s the Andromeda Galaxy, 135 subs x 20s

I’m still refining my technique, but here’s my current processing workflow~

Downloads

• Siril https://siril.org/tutorials/seestar/

• Graxpert https://graxpert.com/docs/2-download/

Siril

1. I run the script to stack the images
2. Image Processing > Remove Green Noise
3. Tools > Astrometry > Image Plate Solver
4. Image Processing > Color Calibration > Spectrophometric Calibration
5. I crop before saving as Linear to process in Graxpert

Graxpert

1. I load the saved *.fit file
2. Background Extraction using AI as Interpolation Method
3. Denoise Image
4. Save again to stretch in Siril

Siril

1. Image Processing > Stretches > Generalised Hyperbolic Stretch Transformations

I don’t have any processing tips to share since I’m still deep in the learning process myself. I attempted several other targets but didn’t achieve results that were significantly better than what the Seestar app produces automatically.

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It’s been a frustrating month overall, but I’m hopeful for clearer skies in August.

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That’s it for now! Stay tuned for more stargazing stories.

🌹