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MarkInSpace
27-09-2023, 06:30 PM
It's nearly time for Halloween, so maybe that's why my new GSO 10" F/4 is giving me a scare.
What would cause bright stars to look "hairy" and make the spider vanes appear split?
I've included a single sub...

rmuhlack
27-09-2023, 07:02 PM
Hi Mark. I believe the "hairy' stars are the result of diffraction artifacts from the primary mirror clips, while the split large diffraction spikes are because the secondary vanes are not properly aligned with one another.

I had similar behaviour with my Skywatcher 200PDS, which were addressed by fitting a mirror mask to the primary and a new CNC milled solid secondary mirror spider, which I purchased from Backyard Universe. https://www.backyard-universe.de/