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Image Solver in PI failed

Pleiades Astrophoto PixInsight Processing Galaxy Cluster
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Johannes Teupen avatar
Johannes Teupen avatar
I took the Leo galaxy cluster in the best conditions, all images were very sharp, the guiding worked excellently at very low values, around 0.6". When processing the WBPP, the following error message occurred with StarAligment:

 “Scanning star data: done38 stars.
integration:Structure map: done
Detecting stars: done
522 stars found.
Minimum star size: 16 px
* Computing global linear transformation
* Target image: limiting to 47 brightest stars
Matching stars: done
[i] [/i]*** Error: Unable to find an initial linear transformation.<* failed *>

So I couldn't do the SpectrophotometricColorCaibration SPCC in PI either. The values ​​for the ImageSolver were correct for both RA and DEC as well as for ImageScale. Does anyone from the experienced PI users have an idea what mistake I made??
I would be very happy to receive an answer that solves the problem.
CS Johannes
Katelyn Beecroft avatar
Katelyn Beecroft avatar
This may not be the solution, but my image solving was failing earlier this week and it was because my focal length value had been changed. Maybe just double check that the value is entered correctly.
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andrea tasselli avatar
andrea tasselli avatar
I suspect, looking at your other images in your profile, that your PSF is far too large for the target magnitude (this seems to be confirmed by the minimu stars size). Try to lower that in the ImageSolver form to something like 16 or such and see what happens.
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andrea tasselli avatar
andrea tasselli avatar
Not that it really changes anything if you use ColorCalibration.
Johan Bakker avatar
Johan Bakker avatar
Hi Johannes,

I found a post on the PixInsight forum that may be of help; https://pixinsight.com/forum/index.php?threads/registration-error-unable-to-find-an-initial-linear-transformation.21991/

Cheers, Johan
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Johannes Teupen avatar
Johannes Teupen avatar
Katelyn Beecroft:
This may not be the solution, but my image solving was failing earlier this week and it was because my focal length value had been changed. Maybe just double check that the value is entered correctly.

Thanks, Kathelyn, but this wasn't my mistake, I specified the focal length correctly.
CS
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Johannes Teupen avatar
Johannes Teupen avatar
andrea tasselli:
I suspect, looking at your other images in your profile, that your PSF is far too large for the target magnitude (this seems to be confirmed by the minimu stars size). Try to lower that in the ImageSolver form to something like 16 or such and see what happens.

Hello Andrea, what is "PSF"?
Tian Tian avatar
Tian Tian avatar
Try it.
andrea tasselli avatar
andrea tasselli avatar
Johannes Teupen:
Hello Andrea, what is "PSF"?


Point Spread Function, that is star size.
Johannes Teupen avatar
Johannes Teupen avatar
Hello Tian,
that is the solution. It worked great. Thanks!!
CS Johannes
PhotonPharmer1 avatar
PhotonPharmer1 avatar
andrea tasselli:
I suspect, looking at your other images in your profile, that your PSF is far too large for the target magnitude (this seems to be confirmed by the minimu stars size). Try to lower that in the ImageSolver form to something like 16 or such and see what happens.

This is probably going to be the answer you need.
Tian Tian avatar
Tian Tian avatar
You're welcome.
Greg Erianne avatar
Greg Erianne avatar
Johannes Teupen:
I took the Leo galaxy cluster in the best conditions, all images were very sharp, the guiding worked excellently at very low values, around 0.6". When processing the WBPP, the following error message occurred with StarAligment:

 “Scanning star data: done38 stars.
integration:Structure map: done
Detecting stars: done
522 stars found.
Minimum star size: 16 px
* Computing global linear transformation
* Target image: limiting to 47 brightest stars
Matching stars: done
[i] [/i]*** Error: Unable to find an initial linear transformation.<* failed *>

So I couldn't do the SpectrophotometricColorCaibration SPCC in PI either. The values ​​for the ImageSolver were correct for both RA and DEC as well as for ImageScale. Does anyone from the experienced PI users have an idea what mistake I made??
I would be very happy to receive an answer that solves the problem.
CS Johannes

Hi Johannes,

Have you tried opening a master light file, then opening the FITS header for it (File | FITS header), and dragging the triangle from the FITS header box to the image you're trying to plate solve?  Once you do that, run Image Solver.  If it runs successfully, you'll be able to run SPCC on your image.

Sorry, I think I tried to solve the wrong problem for you!  This solution will come after your StarAlignment...  apologies.

Greg
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Bill McLaughlin avatar
Bill McLaughlin avatar
I would also check to see that the fits file has the correct (or close to correct) RA and Dec. If those are way off due to some error in acquisition, it will fail. I then typically do a blind solve in other software and then edit the RA and Dec in the fits header and then rerun image solver. It will then work.

They really need to not assume that the RA and Dec in the header are close and initiate their own blind solve if it looks like they might be off. Other SW does this so I find it odd that something as sophisticated as PI does not.
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Wolfgang Bernhardt avatar
Wolfgang Bernhardt avatar
Be also aware of the fact that resolution changes when using drizzle files! I.e. you must divide focal length or pixel size by 2.
Chris avatar
Chris avatar
Wolfgang Bernhardt:
Be also aware of the fact that resolution changes when using drizzle files! I.e. you must divide focal length or pixel size by 2.

Hmmm...was totally unaware of this.

I use APP to stack...PI to post process.  I usually stack using drizzle in APP.

I haven't had a problem solving for the most part in PI (save the one time I input the FL incorrectly).  

Will have to play around with the settings to see if this changes anything but again...havent been having a problem solving with my stacks so far.
Darko Škrlec avatar
Darko Škrlec avatar
Have you try ImageSolver in PI, before SPCC? You  stacked image in APP, maybe your image haven't astrometry data for SPCC.
Johannes Teupen avatar
Johannes Teupen avatar
First I stacked in APP, then Image Solver and thereafter SPCC in PI. I have already solved the problem with the help of Tian Tian:  I have activated the online star catalog PPMXL