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Old 21-02-2016, 03:26 PM
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theodog (Jeff)
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Quote:
Originally Posted by pmrid View Post
........ occurring BETWEEN subs. i.e. one sub finishes, there is a pause for the download and guider settle - up to 20 seconds or so on my QSI CCD and in that period between subs, something happens to allow this drift.

Peter
Peter, I think they are hot pixels (due to the repeat pattern above left).

Are you using a dithered guide? One where the camera is moved several pixels to move hot pixels between frames. If not, than it maybe flexure -don't see how though, perhaps in the focuser unit (very slight sag).
Check your software for any ability to change the strength of hot pixel removal -sometimes dark-frame subtraction just doesn't seem to get all the hotties.
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