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Old 27-05-2018, 11:30 PM
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Stonius (Markus)
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Join Date: Mar 2015
Location: Melbourne
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Thanks for putting that up!

I have questions as to its use;

1) Target Brightness; Stupid question, but what does the p in p/m2/s/arcsec2 stand for? I see that it requires in-the-field measurements - does that mean the intended use is not as a preparatory tool, but more as an on-site drilling down into what the histogram is showing?

2) Gain - I'm confused about the difference between the gain setting on the camera and its actual value in ADU's. Is unity gain (139) where all 20,000 electrons in a well are distributed among the 4096 possible values in 12 bit ADC? That would make it 4.88 e/ADU. at unity gain. Is that correct? I have no idea how to work out the gain for other levels though. Or do I just put in '139'?

3) In band QE; The peak QE of the 1600 is 60%. Reading the relative graph which is scaled to 100% (one assumes 1 = 60%QE because it's *relative QE). So for Ha at 656nm the *relative QE is about .78, which is to say, 0.78 of 60% = 46.8% actual QE in Ha, right?

4) Total exposure time. Why whole hours only? Surely there are some who would like to do less? Maybe not for NB, but the RGB sheet is the same? Seems an odd restriction but what do I know?

5) Reading the results; so I guess I'm looking for the point of diminishing returns here? The point where the graph flattens out?

Best

Markus
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