Astro pixel processor weird final stacked image.

[LaurenceT]

Last night I took a series of 2 minute guided subs of the Elephants Trunk Nebula. After culling I was left with 72 subs which I stacked in APP and finished up with this weird image I've never come across before, no post processing has been done. Explanations gratefully received.

Askar FMA180, Az GTi Asiair Pro.

 

[tomato]

I’m assuming you are referring to the odd overlay of some of the frames?

This is because some of the frames were taken with different rotation orientation and APP has had to rotate them to align the stars with the others. Something has changed on your set up at some point to produce this effect, I see it a lot if I combine historic data, as I’m afraid I am not disciplined enough about the camera position each time I set up.

[LaurenceT]

9 minutes ago, tomato said:

I’m assuming you are referring to the odd overlay of some of the frames?

This is because some of the frames were taken with different rotation orientation and APP has had to rotate them to align the stars with the others. Something has changed on your set up at some point to produce this effect, I see it a lot if I combine historic data, as I’m afraid I am not disciplined enough about the camera position each time I set up.

Thanks, so essentially something rotated during the session?

[LaurenceT]

I've worked out what happened, I followed on @tomato other suggestion about historic data and discovered other data for that target from different dates in the Lights directory on the Asiair usb drive, no idea how that happened. I should have realised something was amiss when I was culling the images in AsiStudio and saw an image of the Globular Cluster in Hercules!

[Adam J]

On 10/01/2024 at 11:19, LaurenceT said:

Last night I took a series of 2 minute guided subs of the Elephants Trunk Nebula. After culling I was left with 72 subs which I stacked in APP and finished up with this weird image I've never come across before, no post processing has been done. Explanations gratefully received.

Askar FMA180, Az GTi Asiair Pro.

 

good start, try using the Light pollution removal tool in APP it's very good and will balance your background. There is also a cropping tool in APP that you can use, I would crop the image first. 

[LaurenceT]

14 hours ago, Adam J said:

good start, try using the Light pollution removal tool in APP it's very good and will balance your background. There is also a cropping tool in APP that you can use, I would crop the image first. 

Thanks Adam, I have used Graxpert stand alone application but it removes almost all of the nebulosity! This is what I finished up with:

 

 

[tomato]

APP LP removal tool works well when you have 'clear' background sky surrounding your target, not so good when the nebulosity fills the entire FOV as in your image.

[ollypenrice]

This is a situation in which 'stacking the stacks' can be better than stacking in one go. Make two stacks, one from each orientation, then co-register one to the other, crop the edges of the co-registered image and then stack it with the base image. Whenever you combine images it is vital to edge crop them because edges always have artifacts.

Olly