I am fairly new to astrophotography and last December I captured a 300s image of Andromeda M31 using ASIAIR pro and a William Optics GT81 with an Asi294MC Pro camera.
For a single exposure I thought it was ok and did basic processing to make it better and it turned out ok. I realise that stacking is required so when we finally got some clear nights here in the UK I decided to get 30 subs of M31 last night. I had to abandon the session as even though I was using less exposure (180s) the images had strange pixel artefacts as seen in the image attached. Please could someone explain what the coloured pixels could be as before this image I has taken 30 subs of the Elephant trunk nebulae and they were fine. Any help much appreciated. Thanks. Nigel