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Help with unknown CCD artifact

Celestron EdgeHD 9.25" Acquisition H-alpha Deep Sky Artifacts
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scoffx avatar
scoffx avatar
Anybody know what is causing this kind of artifact near some stars in my image?  Click here to see.  The dark streak appears only near the brightest of stars.  The streak is not a stacking problem since it exists in every raw image.  This image was a 15min exposure and I noticed that the streaks are less apparent when exposures are shorter (i.e. streak in 5min exp was way less noticeable)

Thanks!
Details:
Stack of 12 x 15min Ha 2x2 at -20C.

Camera: QHY 16200a
OTA: EdgeHD 9.25
0.7 reducer
Moonlite focuser
Astrodon Ha 3nm
Engaging
HR_Maurer avatar
HR_Maurer avatar
Hi Scoffx,
im not sure what causes this, but ive been reading about such artifacts before. I think it is caused by saturation effects during readout. Possibly you could try reducing readout rate/sampling rate. Maybe you could try lower gain settings, too.

CS Horst
Kevin Morefield avatar
Kevin Morefield avatar
I believe that is called blooming.  Though I am used to seeing at as light rather than dark.  Can you check your cameras driver software and see if there is a anti-blooming option to either turn on or off?
Concise
Nikita Misiura avatar
Nikita Misiura avatar
I have the same camera and I get this artifact when I set high readout speed. Just don't use it and this should go away!
scoffx avatar
scoffx avatar
Thanks everyone for the feedback.  I'll check the readout speed setting.  Someone also indicated this might be a problem when binning 2x2.
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Tian Li 李天 avatar
Tian Li 李天 avatar
If this is 16200, then simply set the readout speed to low will solve this
Bfred avatar
Bfred avatar
Scoffx,
Are  you using darks or bias frames?
What processing software are you using?
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