What's this likely to be ?

[Hals]

At the top left of the partially processed image there are curved artifacts.

My first impressions are a light leak from somewhere.

The image consists of x21 luminance frames, calibrated with a master dark and x30 flats\dark flats.

The "light leak" shows up in each of the L subs. I haven't made any changes to the optical train, which is camera, filter wheel, spacers and coma corrector.

This hasn't appeared in any other images I have done recently. 

I did consider next doors security light but it wouldn't show up on all the subs?

Possibly the Moon, but the artifacts look as if they're coming from the North in this image orientation.

The scope is a 150PDS.

It's got me flummoxed, if that's the correct way of spelling it!

Any help or advice is greatly welcomed.

Pete.

Edited March 21, 2021 by Hals
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