Alnitak region (horsehead / flame) with double diffraction spikes

[Robculm]

Finally some clear skies and managed a couple of sessions on this area with the modded camera (also using ES UHC filter).

Both are ~ 3h total integration (5min exposures). First image was early Feb, with no moon, 2nd image (where I've also tried to frame in the flame) was this past week, with ~70% moon.

Alnitak makes this quite a challenge and I'm wondering if anyone has any thoughts as to why I'm getting these very long double diffraction spikes?

Cheers, Rob

 

[barbulo]

I would say either slightly out of focus or the spider vanes changed position between sessions (camera or OTA rotation).

[ollypenrice]

The orientation of the spikes relative to the sky is the same on both images. That means that the OTA has not rotated in the tube rings so presumably the camera has rotated.

I think the split may be caused by a twist in the vanes but I'm not well up on Newt imaging.

Olly

PS Somewhere along the line, green has replaced blue in this processing. This means your blue is somehow being suppressed, either at capture or in processing.

Edited January 16, 2022 by ollypenrice
PS

[Robculm]

Thanks both for your comments. Camera was removed between sessions & of course re-focussed each time, so must be something 'fundamental' in the set up, not specific to these sessions. Spider vanes all look good, so I'm still at a loss on the root cause here!

Any other suggestions welcomed. I will try to set up a very bright artificial star test & see how it looks...

Cheers,

Rob

[Robculm]

And yes, colours are a bit subjective! I'm using the UHC filter so there shouldn't be much green there to begin with, so just my processing that's to blame on that one!