STF-8300 Random white marks in Dark frame

Discussion in 'STF Series CCD Cameras' started by John Symeonidis, Jul 12, 2016.

  1. John Symeonidis

    John Symeonidis Standard User

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    Taking dark frames at home 1200sec @-10C I noticed white marks appearing randomly. Any idea what causes these? These pics are from a small area of the Darks Darks_1200_1.jpg Darks_1200_2.jpg
     
  2. Colin Haig

    Colin Haig Staff Member

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    Looks like cosmic ray/gamma ray hits to me.
     
  3. Doug

    Doug Staff Member

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    Colin is correct. That's why we recommend using median or sigma clip when stacking, it gets rid of them.
     
  4. rpineau

    rpineau Standard User

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    I see similar one on 600 seconds dark frame (I'm in the process of fully redoing my dark library after the latest firmware upgrade).
     
  5. John Symeonidis

    John Symeonidis Standard User

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    Colin, Doug do you suggest that I have cosmic or gamma ray inside my room?. Is there a way avoid them?
     
  6. Colin Haig

    Colin Haig Staff Member

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    A few kilometres of rock above you will help a bit with the cosmic rays, and heavy lead (Pb) or paraffin shielding for the gamma rays. ;-)
    They are a natural occurrence, and can't really be avoided. Save a few of them to share with your friends - the cosmic ray photons came a long way to light up your camera's pixels.
     
  7. Doug

    Doug Staff Member

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    Just be thankful for the earth's atmosphere. This does get worse at higher elevations.

    Some of the radiation may actually be from building materials like concrete and drywall. There's some level of natural radioactivity in most materials.
     
  8. John Symeonidis

    John Symeonidis Standard User

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    Doug, Colin thanks for your reply
     

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