11 replies to this topic

[skysurfer]

Using Siril 1.22 on macOS I loaded a picture of Orion centered around M42 and selected burger menu ‣ Image Information ‣ Image Plate Solver.
The image is made with a Canon R6 DSLR and a 100-400L set to 200mm.
Then I filled in 'M42' which resulted in the correct coordinates of the Orion Nebula. And as the image is 2160x1440, the pixel size is about 15um. What I noticed, orientation of the image was missing as parameter. It is an image with south up, so I rotated 180 degrees but to no avail.
I tried all catalogs, but to no avail.
When I don't check 'crop', then it tells image size is about 11 degrees which did not work, so I selected 'crop' and it cropped to 5 degrees, but without success.

 

How can I plate solve with Siril ?

19:08:31: Loading script: RGB_Composition

19:08:31: Searching scripts in: "/Users/user/siril/scripts"...

19:08:31: Loading script: [DSA] Star Reduction-MTF

19:08:31: Loading script: DSLR_preprocessing

19:08:31: Loading script: DSLR_preprocessing_Cosmetic

19:08:31: Loading script: DSLR_Preprocessing_Drizzle

19:08:31: Loading script: DSLR_preprocessing_Drizzle_Cosmetic

19:08:31: Loading script: DSLR_Preprocessing_NoDark

19:08:31: Loading script: DSLR_Preprocessing_NoFlat

19:08:31: Loading script: DSLR_Preprocessing_NoFlat_NoDark

19:08:31: Loading script: DSLR_Preprocessing_NoFlat_NoDark_NoBias

19:08:31: Loading registration method: 1-2-3 Stars Registration (deep-sky)

19:08:31: Loading registration method: Global Star Alignment (deep-sky)

19:08:31: Loading registration method: Two-Pass Global Star Alignment (deep-sky)

19:08:31: Loading registration method: Image Pattern Alignment (planetary - full disk)

19:08:31: Loading registration method: KOMBAT (planetary surfaces or full disk)

19:08:31: Loading registration method: Comet/Asteroid Registration

19:08:31: Loading registration method: Apply Existing Registration

19:08:31: Default FITS extension is set to .fit

19:08:31: New version is available. You can download it at <a href="https://siril.org/download/1.2.1">https://siril.org/download/1.2.1</a>

19:08:43: Reading FITS: file orion.fits, 3 layer(s), 1440x2160 pixels, 16 bits

19:08:53: There are no keywords stored in the FITS header.

19:09:27: Plate solving image from an online catalogue for a field of view of 5.00 degrees, using a limit magnitude of 10.87

19:09:27: Catalog NOMAD size: 532 objects

19:09:27: Findstar: processing for channel 1...

19:09:27: Using 158 detected stars from image.

19:09:28: Plate Solving failed. The image could not be aligned with the reference stars.

[lock042]

Hello.
Pixel size of 15µm look suspicious.

[skysurfer]

Hello.
Pixel size of 15µm look suspicious.

What is suspicious on it ?

The image is 2160x1440 and covers 10 by 6.6 degrees.

10 degrees is 36000" so a pixel is 36000/2160 = 16.6" per pixel. So the 15 degrees is (almost) correct.

Unfortunately, Siril does not have the possibility to fill in the image size in degrees rather than pixel size. Image size is easier to obtain.

And an orientation field is also missing, pictures are not always north up.
 

[OzViking]

According to this review (about half way down the first page, https://photographyl...ws/canon-eos-r6 ) the pixel size of the camera sensor is 6.58µm.

 

I suggest entering that value into the 'Pixel Size' box and trying to plate-solve again.

 

Regards,

V.

[lock042]

What is suspicious on it ?

The image is 2160x1440 and covers 10 by 6.6 degrees.

10 degrees is 36000" so a pixel is 36000/2160 = 16.6" per pixel. So the 15 degrees is (almost) correct.

Unfortunately, Siril does not have the possibility to fill in the image size in degrees rather than pixel size. Image size is easier to obtain.

And an orientation field is also missing, pictures are not always north up.
 

I think you're confusing a lot of notions.
Here we're just asking for the size of a camera pixel, a photosite to be more precise.

[EdFromNH]

I agree with the comments about correct pixel size. But I also get a lot of plate solve fails with Siril. Even with “flip” selected as an option, I find manually flipping first often solves the problem. If that does not work, I upload to https://nova.astrometry.net/ and download the solved fit it generates.

[Der_Pit]

What is suspicious on it ?

The image is 2160x1440 and covers 10 by 6.6 degrees.

10 degrees is 36000" so a pixel is 36000/2160 = 16.6" per pixel. So the 15 degrees is (almost) correct.

Unfortunately, Siril does not have the possibility to fill in the image size in degrees rather than pixel size. Image size is easier to obtain.

And an orientation field is also missing, pictures are not always north up.
 

It's not asking for the "/px, but for the (physical) size of the pixels in microns.  From that it is computing the image scale.  If the image has not been binned you would (for a 200mm lens) get an image scale of (6.58/200)*206.265 = 6.786"/px.  So obviously it's not the original scale, but has been binned/interpolated/cropped.

 

By chance, for a 200mm lens pixel size in micron and scale in "/px are almost the same (206.265/200 = 1.03), so your approach should have worked.  To me that would suggest it is a problem with the star finding algorithm.  Maybe check (in Dynamic PSF) what stars it finds with the current settings, and adjust them so the found stars are reasonable.  Remove the selection found before you go back to platesolve...

[lock042]

No chance it works with the value of 15microns

[Tony_Gondola]

+1 for pixel size.

+1 for plate solving often fails in Siril (and usually it's my fault)

 

Best advice, don't over-think it and give Siril the data it's asking for. Its asking for the pixel size of your sensor in microns.

[skysurfer]

The pixel size is only valid when using the full resolution : 5472 x 3648. But the image I use in 2160 x 1440, so each pixel of this image is considerably larger in arc seconds: (5472 / 2160) * 6.58 = 16.67" per pixel, so even a bit more than 15.

[Tony_Gondola]

How are you getting to 2160x1440? Are you binning by 2.53x somehow or is it region of interest?

[lock042]

Are you doing plate solving on linear data?