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Unable to plate save M51 from Telescope Live

Craig Steele
in PixInsight
I have been unable to plate solve M51 from Telescope Live. I have included the file (stacked RGB Master) and a screen shot picture of the Telescope and Camera data from telescope live. The image is from the CMOS camera. I initially submitted a query on the Pixinsight Forum, but was unable to come to a resolution on how to proceed. I figured I would ask the master.

Craig 


Comments

  • BlockHeadBlockHead
    HI Craig,

    It is hard to believe I can do better...
    but let's begin. What telescope did you use and what parameters did you put in your IMageSolver?

    -the BLockhead
  • Craig Steele
    Hi Adam,

    The Telescope Live data is as follows:

    Scope: Stellare 700 RC
    Aperture: 700 mm
    Focal Length: 5,600 mm

    Camera: QHY 6000m Pro
    Pixel size: 3.76s um
    Pixel Array 9,576 x 6382
    Binning 4

  • BlockHeadBlockHead
    edited April 5
    OK.. is the problem that YOU cannot plate solve the image or that you believe others cannot?

    PixINsight solves the image. You have 15um pixels (because you are binning by 4). 
    However because the image quality is TERRIBLE... the seeing has made the stars quite large.

    So input 15um for the pixel size and 0.33 for the resolution. It solves. See below.
    The actual answer is 0.5" per pixel which does mean a 5600 focal length like you expect. 

    So, PI solves the image. 

    ==================================================================================================

    Creation time ............ 2025-04-05 00:12:53 UTC

    Creation software ........ PixInsight 1.9.3 / ImageSolver 6.3.1 (Windows)

    Reference catalog ........ Gaia DR2

    Linear transformation matrix (native[l,b] = matrix * image[x,y]):

    -1.52974234e-04 -3.30139553e-06 +1.84408677e-01

    +3.28910117e-06 -1.52925310e-04 +1.16404271e-01

    WCS transformation ....... DDM thin plate spline

    Control points ........... 105

    Spline lengths ........... l:105 b:105 X:105 Y:105

    Projection ............... Gnomonic

    Projection origin ........ [1188.509413 786.746151] px -> [RA: 13 29 52.267 Dec: +47 11 37.58]

    Resolution ............... 0.551 arcsec/px

    Rotation ................. 1.243 deg

    Reference system ......... ICRS

    Observation start time ... 2023-04-23 01:29:17 UTC

    Observation end time ..... 2023-04-23 04:00:10 UTC

    Focal distance ........... 5617.77 mm

    Pixel size ............... 15.00 um

    Field of view ............ 21' 49.7" x 14' 26.9"

    Image center ............. RA: 13 29 52.268 Dec: +47 11 37.58 ex: -0.003548 px ey: +0.001630 px

    Image bounds:

    top-left .............. RA: 13 30 57.471 Dec: +47 18 34.73 ex: -1.115912 px ey: -1.098423 px

    top-right ............. RA: 13 28 48.742 Dec: +47 19 02.95 ex: +0.023279 px ey: -1.773919 px

    bottom-left ........... RA: 13 30 55.357 Dec: +47 04 09.12 ex: -1.098715 px ey: +0.433340 px

    bottom-right .......... RA: 13 28 47.198 Dec: +47 04 36.90 ex: +0.008815 px ey: +0.433271 px

    ==================================================================================================



  • Craig Steele

    Even When I put 15 for the pixel size and .33 for the resolution I am unable to get it to solve. Others on the Pixinsight forum have solved it with those values, but when trying to solve this image I get the following. I can easily solve other targets...but not this one.



    0 star pair matches found - need at least 3 matched stars.

    * Previous attempt failed - this is try #6

    * Reference image: limiting to 8 brightest stars.

    * Target image: limiting to 8 brightest stars.

    Matching stars: done


    ** 0 star pair matches found - need at least 3 matched stars.

    *** Error: Unable to find an initial linear transformation.

    <* failed *>


    *** Error: The image could not be aligned with the reference star field.

    Please check the following items:

    • The initial center coordinates should be inside the image.
    • The initial image resolution should be within a factor of 2 from the correct value.
    • If you use an online star catalog through the VizieR service, consider using the Gaia DR3 catalog with local XPSD databases instead.
    • If the image has extreme noise levels, bad tracking, or is poorly focused, you may need to adjust some star detection parameters.


  • Craig Steele
    Ok, this is something totally new to me. I reread the error message. ***Unable to find an initial linear transformation***

    I stretched the image, and it solved. Why would it solve an image only when stretched? 
  • BlockHeadBlockHead
    It is because the stars are too big. By stretching the image..you made some of the fainter stars have a PSF that is somewhat reasonable. The problem boils down to the poor image quality. It needs to detect stars in order to plate solve...or things do not work. 

    YOu said you put in 0.33..but you also needed to use the other value of 12um. You and I need to agree when I find a solution that works...it works for you as well. Computers are deterministic machines...we will get the same answers if we both do the same things

    -the Blockhead
  • Craig Steele
    Thank you for helping me work through this issue. I now have another "technique" to help me as I progress in this hobby. 

    Craig
  • BlockHeadBlockHead
    There is perhaps a better solution. If you have BlurXTerminator- this will both sharpen and regularize the stars in such a way that ImageSolver will not have an issue. This has the additional benefit of keeping the image linear.

    -the Blockhead
  • Craig Steele
    Thank you for the tip. Image solver is typically the first thing I do, But I can see now how the workflow may need to be adjusted at times. 
  • BlockHeadBlockHead
    I guess you really only need to platesolve your masterlight frames. They will have the best data to work with...we hope.

    -the Blockhead
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