Bisque ME+ and SBIG STXL camera and FW8G-STXL

Discussion in 'General' started by Alan Berkowitz, May 2, 2020.

  1. Alan Berkowitz

    Alan Berkowitz Standard User

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    I am setting up my ME+ \Camera\guider. My observatory is a roll off building. I have run a 100 shot TPoint and have very good pointing. I have performed an accurate polar alignment and it seems quite good as well. I have run a PEC model. I activated Protrack as well. I sent the telescope to M81. I include a 10 minute image with the red filter.

    As one can see my guiding for 10 minutes on the R filter is quite poor even though the graph in Maxim shows less than +\- 1. In fact it appears that the stars are moving in a circular motion around M81. I include pictures of my guiding settings as well. Any feedback would be very appreciated.
     

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  2. Alan Berkowitz

    Alan Berkowitz Standard User

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    i forgot to mention that the telescope above is an apochromatic refractor with a focal ratio of F7.8 and is 8.2 inches in diameter
     
  3. Doug

    Doug Staff Member

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    What are you using for the guider?
     
  4. Sreilly

    Sreilly Cyanogen Customer

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    That what I was thinking. Is it a guide scope/camera in which case you could have flexure between the main scope and guide scope? Are you using a OAG? Camera with internal guide chip?
     
  5. Sreilly

    Sreilly Cyanogen Customer

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    Actually looking at the image you notice the star movement is in different directions? The stars center of the image look like they move horizontally while the stars on the left and right look to be at 45 degrees but in different motion. It's as if you have a rotator and it still moving very slowly counterclockwise. Check and make sure all the gear is solid and tight. Cables out of the way. I think I saw this once before on an Alt/Az mount.....
     
  6. Alan Berkowitz

    Alan Berkowitz Standard User

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    The onchip guiding uses the telescope itself. The filter wheel has a guiding chip.
     
  7. Sreilly

    Sreilly Cyanogen Customer

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    Is there a reason for Anti-stiction to be set at all?
     
  8. Alan Berkowitz

    Alan Berkowitz Standard User

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    Also, the gearing is set and locked on the mount.
     
  9. Alan Berkowitz

    Alan Berkowitz Standard User

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    I set the antistiction as per the instructions on how to do the guiding after the image was taken
     
  10. Alan Berkowitz

    Alan Berkowitz Standard User

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    The mount is a German equatorial
     
  11. William B

    William B Cyanogen Customer

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    Alan, I'm with Sreilly and his assessment that something else is moving in the image chain.

    There is no way that a guiding error can cause the stars in an image to rotate in different directions in a single image.

    Your camera, a camera coupler, the focuser coupling or the entire OTA is a little loose and rotating in the tube rings as the exposure is underway.
     
  12. Doug

    Doug Staff Member

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    It really looks like the polar alignment is waaaaay off. That would cause the image to rotate around the guide star.
     
  13. Sreilly

    Sreilly Cyanogen Customer

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    Should be easy enough to tell by taken a 60 second unguided image. More dramatic in 300 seconds.
     

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