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Old 02-02-2014, 11:24 AM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,831
Quote:
Originally Posted by Bassnut View Post
WHAT!. A typical Ha 3nm 40min bin 1 sub on my SBIG gives 1100 odd ADUS back ground uncalibrated and 50 after calibration. Bias subs show about 1000 ADUs. Are you saying I need to increase subs to several hrs for best S/N?.

Have I missed something?, my 50 ADU background after calibration, is that what you mean by "above bias"?.

What about blooming on an NABG cam!. Several Hr subs would be unusable?.
Fred
just realised that your calibration process is removing dark current and that is part of the background signal for NB - your "above bias" background signal is about 100 ADU rather than 50, so your background noise is about 10 electrons, not 7. Makes no difference to the earlier conclusion, your system is still read noise limited and would benefit from much longer subs. Regards ray

Last edited by Shiraz; 03-02-2014 at 08:43 AM.
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