Photographic artefact - what could be causing it?

[Bugdozer]

Here's one of a set of sub frames I took a couple of nights ago. I have brought up the exposure to show the odd green streak in the picture.

This is definitely NOT a real object in the sky. It's in all the frames but sometimes looks slightly different in shape or has a different position relative to the background stars. I can't figure out what's causing it, though. My first thought was that it could be something akin to lens flare from one of the two bright stars in the frame, but I have never seen this happen on other photos I have taken with the same lens (Tamron 70-300 zoom). I couldn't see any other light sources where I was shooting from that could be shining into the camera lens, so I'm a bit stumped as to what's causing this. I realise zoom lenses are not ideal for astrophotography but it's what I've got.

Bonus points to anyone who can work out what I was actually trying to photograph here!

[ONIKKINEN]

Lens flare or reflection would be my guess as well, since its in every frame.

Pretty sure this is the Horsehead and Flame nebula region? Plenty of very bright stars all around to cause some reflections. How does it look if you stack some frames? Might be fixable in Photoshop with some clever lasso tool/content aware fill/healing brush action.

[symmetal]

Normally flares do 'point' to the star causing it but overlaying in Stellarium, nothing stands out as a cause. It's not very 'flare' shaped either which doesn't help. 🤔 It's normally stars out of frame close to the edge of the scopes FOV which cause flares rather than stars in the frame.

Alan

Edited March 9 by symmetal

[Bugdozer]

If it's a star out of the frame, then the culprit would have to be Mintaka, just away to the top right. As to when I stacked them, the streaks blurred out into a smeared cloud. I wasn't massively bothered because the quality of the stack wasn't as good as it should be anyway (condensation started up halfway through the sequence and I didn't notice) so I will be repeating this shot, but maybe a slightly different framing will get rid of the streak.