Bright corner of first exposure

Discussion in 'STX and STXL Series Cameras' started by VictoriaSaucier, Oct 25, 2019.

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  1. Colin Haig

    Colin Haig Staff Member

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    Hi Mark,
    Can you send over some recent sample images?
    How big is a "large portion" ?
     
    Colin Haig, Jan 10, 2022
    #21
  2. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Hi Colin,

    Here's an example. It varies every subexposure, so it does not calibrate out. This is a combined image of calibrated subexposures. It effectively prevents gradient removal. Untitled-1.jpg
     
    Mark de Regt, Jan 10, 2022
    #22
  3. Colin Haig

    Colin Haig Staff Member

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    Thanks - discussion with @KrisW in engineering underway.
    We'll probably want a batch of raw 1x1 bias, dark, lights.
     
    Colin Haig, Jan 10, 2022
    #23
  4. Doug

    Doug Staff Member

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    We've tried but we still can't replicate the phenomenon with our in-house test camera. (And, previously, I couldn't replicate it with my former observatory camera.)

    What is the serial number of your STX?
     
    Doug, Jan 10, 2022
    #24
  5. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Interesting; there's a lot of chatter out there about the amp glow on this camera, and I have talked to others who have the same problem.

    I have sent you an email with the screen grab of the camera info from CCDOps.

    Mark
     
    Mark de Regt, Jan 10, 2022
    #25
  6. Doug

    Doug Staff Member

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    That may be; but there's something weird going on here because we can't reproduce the problem. We're still investigating.

    Screen grabs aren't of much use to us. We need FITS images.
     
    Doug, Jan 11, 2022
    #26
  7. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Fine; tell me what you want, and I'll upload it for you to download.
     
    Mark de Regt, Jan 11, 2022
    #27
  8. KrisW

    KrisW Moderator

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    Hi Mark. I'm the hardware engineer trying to reproduce your issue. Could you please tell me what was your sensor temperature and exposure time? Or send us a raw frame with the visible amp glow? All the information we need should be in the FITS header. Thank you.
     
    KrisW, Jan 11, 2022
    #28
  9. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Mark de Regt, Jan 11, 2022
    #29
  10. KrisW

    KrisW Moderator

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    Thank you Mark. Unfortunately, I can't download the files and get this message: de-regt.com refused to connect.

    So you say that only light frames? That's an interesting clue.

    I have two hypotheses I'm testing.

    Another one is a possible RBI effect accumulating in-between exposures. Is it possible that the longer the idle period between exposures, the brighter the amp glow? Maybe you take breaks between light frames, but have no breaks between taking dark frames? The more clues we have, the better.
     
    KrisW, Jan 11, 2022
    #30
  11. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Bizarre; I can reach it sometimes with that link, but not most of the time. I hate gremlins!

    Is there another way I can get the file to you? It's 16MB, so I don't think I can email it.

    The only break between light frames is downloading the just-finished frame, recentering, and starting the AO-X. There is no delay between dark frames.

    That frame is a 30-minute image, at -25C. But there is some glow in almost every frame, regardless of duration.
     
    Mark de Regt, Jan 11, 2022
    #31
  12. Colin Haig

    Colin Haig Staff Member

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    Colin Haig, Jan 11, 2022
    #32
  13. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Thanks, Colin!
     
    Mark de Regt, Jan 11, 2022
    #33
  14. Doug

    Doug Staff Member

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    We just had a breakthrough on this. The investigation was complicated by the fact that only some sensors exhibit the behavior! Also it can depend on certain bias voltage adjustments. No wonder it was so hard to replicate. Once we managed to coax a sensor into doing it, we were able to isolate the issue pretty quickly.

    The root cause is that the amplifier glow somehow creates residual bulk image while the camera is idle! This happens despite the fact that the sensor is continually flushing. Pretty weird stuff - must be related to the specific construction of the on-chip readout amplifier.

    We have a solution, but we need to put our heads together to figure out how best to roll it out. It may involve logging in on Teamviewer to tweak a camera setting.
     
    Doug, Jan 11, 2022
    #34
  15. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Excellent news!

    I look forward to the solution!

    Mark
     
    Mark de Regt, Jan 11, 2022
    #35
  16. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Any update (as the moon starts to wane)?
     
    Mark de Regt, Jan 17, 2022
    #36
  17. Colin Haig

    Colin Haig Staff Member

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    Colin Haig, Jan 17, 2022
    #37
  18. Mark de Regt

    Mark de Regt Cyanogen Customer

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    Ok, thanks for the update.

    Good luck out there!
     
    Mark de Regt, Jan 17, 2022
    #38
  19. Adam Robichaud

    Adam Robichaud Lead Developer Staff Member

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    Hi Mark, Kris has given me the instructions to apply the solution to your camera. Could you make your camera available to me via TeamViewer? If you can get me your connection credentials in a private message I'll tackle this ASAP.
     
    Adam Robichaud, Jan 18, 2022
    #39
  20. Colin Haig

    Colin Haig Staff Member

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    Sent you an email.
     
    Colin Haig, Jan 18, 2022
    #40
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