Alignment of images

[Jules]

Hi Everybody

Just to give you an idea of my background. I am a novice imager.

I have collected several hours worth of Ha data on IC443 (5 to 20 min subs). I have calibrated, combined and aligned the subs in Maxim DL. This always gives a nicely aligned image but fairly noisy.

I thought I would have a go at alignment and integration with Pixinsight. This gives me a lovely image (virtually noise free) for further work but the orientation means the image is going to have a severe crop.

Is there anyway I can align my image so it looks like a rectangle rather than a offset parallelogram? Is there a particular sub causing this, if so how can I find it?

Thanks

Julian

Infant PixInsight user!

[Cleon_Wells]

Jules, if you comb through the Process Console list after you have Registered these subs, you my find several  subs that have a large offset and or rotation.
       A note on the Reference image used for StarAlignment, if you use (View) for the Reference image, (you have opened a sub) and leave this sub file open it will be used as the Reference image for Integration.
       After I stack with Integration and have  Pixel Rejection set to Winsorized Sigma clipping, I will again look at the Process Console Rejection list for any subs that have large rejection numbers.
I hope this will help.
Cleon

[Jules]

Cleon

Thanks for the reply. I shall follow your advice, thanks

Julian

[Cleon_Wells]

Julian, In Registration, I also set Maximum distortion to 0.68 in Star Detection, this removes any of my sub that have poor tracking problems automatically.
Cleon

[Jules]

Cleon

Thanks you very much with your time. I have 30 subs ranging from 5 to 20 minute of Ha data, I opened a reference sub in PI and had a look at the rotations after star alignment. The rotations range from -1 to -6 degrees.

I also applied the maximum distortion as mentioned to 0.68 and no subs were rejected.

After integration the image is still offset requiring a large crop.

Do you have a processing routine, what would be a good routine to follow?

Thanks

Julian

[Cleon_Wells]

Julian, that seem to be a large difference in rotation. I would try using a different Reference sub, maybe one that's in the middle of the 5 degree rotation set. I would like to see a screen shot of the integration before cropping.
There are others on this forum that know a lot more about processing then I do, so maybe some one else can jump in to this thread with some other ideas.
Cleon

[Jules]

Hi Cleon

I tried a another sub an the rotations ar managable now. Thanks a lot for you time!

Regards

Julian