Quote:
Originally Posted by ChrisV
** Warning: No correlation between the master dark and target frames (channel 0).
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This is common with flats where the exposure time is a lot shorter than the darks. Here's what Juan Conejero wrote on one of the many threads about this...
Quote:
Those warning messages are telling you that the master dark frame you are using has no correlation to the light frame in terms of thermal noise. In other words, if the master dark frame is subtracted from that light frame, then the result will always have more noise than the original. Hence, a zero dark scaling factor is being applied, which is equivalent to not subtracting the master dark frame at all.
The noise evaluation routine implemented in our ImageCalibration tool is very robust, so in general my advice is trusting it. We still haven't seen a practical case were it fails to compute an optimal dark scaling factor.
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It's a warning you can safely ignore.
Cheers,
Rick.