Mosaic with 3 panels failed

Vulpescu

Vulpescu

Member
Hello there,
for the first time I wanted to shoot a 3 panel mosaic of M 31. Unfortunately my camera was - especially during the 3rd panel - slightly out of the optical axis. Therefor my stars were a little eggshaped.


1598694326671.png

Thesewere my settings. It did not work because PI said that it could not detect anx stars. The overlay of the panels was 18%, which was optically more than enough.
And "Frame Adaptation" under "Working Mode" was enabled, in difference to the screen shot.
I also tryed RANSAC iterations up to 4000.
I tryied to glue the panals in star alignement in the linear state.
Can someone help my, please?

I apreciate that,
Christian
 

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Last edited:
Maybe try the PhotometricMosaic script from John Murphy to get a better result?

The approach to create the mosaic would be:
  • Calibrate the images
  • For each mosaic frame, register and stack the images
  • Apply DBE/ABE to the stacked images to remove gradients
  • Plate solve the mosaic tiles with the script 'Image Analysis -> ImageSolver'
  • Register the mosaic tiles with the script 'Utilities -> MosaicByCoordinates
Then use the scripts provided by John, e.g. 'Mosaic -> TrimMosaicTile' and 'Mosaic -> PhotometricMosaic'

/Ralf
 
Thank you Ralf, sounds very professionell.
My goal Was to glue the panels together before I do any manipulation like DBE etc. on them.
The data is pretty good but I shot the middle panel on 0 gain because of the bright core of M 31. The other 2 panels run on gain 75. Therefore I want to process All 3 penals glued together from scratch.
I'll try it and will report soon, if it worked.

CS Christian
 
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Christian,

You really want to have the cleanest images before you try to assemble the mosaic tiles. In particular gradients will be hard to fix later.

If you suffer from different background intensities then the 'dnaLinearFit' script from David Ault might help. The script matches varying intensities between images and was specifically developed for mosaics, as it overcomes some problems of the regular 'LinearFit'.

It might be better to acquire all panels with the same camera setting and instead create two identical mosaics with different exposure times. One with a long exposure to get the fainter details, the other with short exposure to avoid saturating the galaxy core.

The two mosaics can be processed with 'HDRComposition' to get the final result that shows the core and the faint details.

Hope this helps.

/Ralf
 
Dear Ralf,
I couldn't be more thankfull for youre geniusly tipps.
I'll try them all.
I've tryed this " HDR Composition" - thing, though. Which didn't work with my data.
Never the less: You are my sun ray!
Don't get it wrong.?
Thank you again and I will try it tomorrow.
Cheers and I will whrite tomorrow if it worked.

CS Christian
 
By the way: This is, what I' ve got allready: (2 and 3 panals):
Vulpescu said:
Dear Ralf,
I couldn't be more thankfull for youre geniusly tipps.
I'll try them all.
I've tryed this " HDR Composition" - thing, though. Which didn't work with my data.
Never the less: You are my sun ray!
Don't get it wrong.?
Thank you again and I will try it tomorrow.
Cheers and I will whrite tomorrow if it worked.

CS Christian
Click to expand...
 
Hey Ralph,
I tryed the whole day. The problem is that I am not familiar with the scripts you recomanded me.
The only one that Was a little breake through was that DNA liniar fit. That hat an impact.
I put the processed panels with the Microsoft Image Composit Editor together.
But I'll keep on practicing with the scripts you told me.
Thank you a lot.
 
Ok. I can completly understand, if you give up on me, Ralph. I am still extremly thankfull for the scripts, you`ve recomanded.
As I said, I`ll work on them. I`m doing Astrophotography sinch 8 months. But I try.
Here is my issue:
 

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Christian,
is this one of the mosaic tiles or is this the complete mosaic? It would be best if you could post the three individual tiles and indicate what you did to calibrate them.
I can see that the core is completely saturated but it is difficult to help you without the original images.
/Ralf
 
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