Strange light on 16803 Frames

Discussion in 'STX and STXL Series Cameras' started by sixburg, Jun 22, 2016.

  1. sixburg

    sixburg Cyanogen Customer

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    Please see the attached which show a strange light artifact in the upper right corner of unprocessed image frames. I suspect some sort of light leak, but have no clue where it's coming from.

    Attachements:
    • Blink movie of light frames;
    Lights are taken from both sides of the meridian with 180 rotation of the camera. The light artifact does not change general area, but varies in intensity. This indicates that the light source follows all rotating components which is the entire image train (AO-X, MMOAG, FW7, STX16803).

    The telescope traversed a significant portion of the sky which nearly eliminates any external stationary point source of light. In addition, the observatory has no significant stray light sources (LEDs taped, or off, etc...all except that crazy blinking AO-X light?!?!)

    https://1drv.ms/v/s!AlAL46Fj3rIerGaQTElPclSrHM2_
    • Plate solve of image area which shows no stars in the affected area of the frame brighter than 10th magnitude. In my experience this is not bright enough to impact the light frame. Plus the 9.99 mag star is not in quite the right position to cause the issue.
    Additionally, this artifact appears on every other light frame in the same place so this eliminates and off-frame star issue.

    Hypotheses?
    1. External source? the observatory is dark. The offending external light would have to be directional to impact only the upper left corner. It would also have to be moving inside the observatory at the sidereal rate. And finally it would have to also move 180 after the flip. This points to something on the image train itself. Maybe something on the back of the scope, but the 180 rotation makes that unlikely. I can ensure that any LED near the camera is blacked out. I cannot guarantee that 100% right now since the scope is 1,500 miles away from me.
    2. MMOAG reflection? I've no clue how this would even come into play since the prism is center and the problem is upper left.
    3. Camera issue? I don't know what could be inside the camera doing anything funny near that part of the chip. I ask that you think about this possibility and advise on this.
    4. Any LED? Since the exposures are 1200 seconds even a blinking LED would appear persistent in the frame; however, it would have to move at sidereal and do a 180...still points to something on or very near the camera that moves at the same rate.
    5. Others?
    Thoughts?

    Thanks,
    -Lloyd​
     
  2. Tim

    Tim Staff Member

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    Are you using new/updated calibration or master frames? Does this occur on un-calibrated images?

    Please send an uncalibrated FITS image showing the artifact that we can inspect.

    What software are you using to capture images?
     
  3. sixburg

    sixburg Cyanogen Customer

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    The images you're seeing are uncalibraed.

    Will send fits later.

    Capture is MDL 6.12
     
  4. sixburg

    sixburg Cyanogen Customer

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    Tim

    You have access to the files.
     
  5. Robert Mueller

    Robert Mueller Standard User

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    Sedona, Arizona
    I see the same glow in the corner of my STXL 11002.
    Robert Mueller
     
  6. sixburg

    sixburg Cyanogen Customer

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    I also uploaded FITS converted from the original XISF. Link is in your email.
     
  7. Tim

    Tim Staff Member

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    All I received was a google drive email from an unknown sender that was labeled as spam, but I do not have access to your files.
     
  8. sixburg

    sixburg Cyanogen Customer

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    I sent a link to FITs version on OneDrive. Also sent it again just now.
     
  9. Tim

    Tim Staff Member

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    I do not see any light artifacts in the image you sent. In addition, there seems to have been a significant amount of post processing done by pixinsight on this image as noted in the image header history.

    We need a completely raw and *unprocessed* image demonstrating the issue.
     
  10. sixburg

    sixburg Cyanogen Customer

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    Tim...
    I was mistaken on the video...those were indeed calibrated files. This new version is of uncalibrated files (you can see the hot pixels which indicate they have not been calibrated): https://1drv.ms/v/s!AlAL46Fj3rIerREHEbT7J6ZvQLqf

    Here is a new link to the unprocessed files in the video: https://1drv.ms/f/s!AlAL46Fj3rIerGqZ5gRSYm0GZMbk. There are 8 frames included. All frames are affected to varying degrees.

    Suffix of most affected frames (included in the batch of 8):
    1. 011214
    2. 010555
    3. 023355

    The processed image would be devoid hot pixels and dead columns and look something like this (hastily calibrated, registered and integrated with no improvements...my bad pixel map does not yet include the dead column(s) to the far right side of the chip): http://www.astrobin.com/253198/. Of course, darks, bias and flats are applied to this image and the offending light persists just as it does in the raw frames (2nd link above). The light is not a product of the darks, flats or bias. I've already checked that. I've already checked to see if it might be a bright star nearby, but not on the chip...not that either unless a mag 9.99 star would cause this from a internal reflection or something (plus the star is in the wrong place). I've seen this before, but from much brighter stars (>= 5th magnitude).

    I tested all the links and they work on this end.

    Thanks for checking this out.

    -Lloyd
     
  11. marc4darkskies

    marc4darkskies Standard User

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    I have the same artefact as well (STXL-11002).
     
    Last edited: Jun 26, 2016

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