BasicCCDParameters script wrong calculations

[AstroScience]

Hi guys, I think I stumbled upon a bug in CCDParameters script, giving false calculations.
I'm not sure, but take a look at the image.
Standard deviation of B1-B2 is 22.079 ADU
Gain is 0.255 e/ADU
both of these match my own calculations, but ReadNoise from the script shows 3.987 e and as far as I know the ReadNoise should be
22.079*0.255=5.6 e
which is making sense with the manufacturer specification.
Have no idea why the script shows 3.9 e of readnoise.

[sharkmelley]

It looks fine to me.

The standard deviation of the difference frame (i.e. B1-B2) is 22.079 ADU
Since the gain is 0.255 e/ADU that means the StdDev of the difference frame is 5.6e

But the difference frame has sqrt(2) more noise than a single frame.

So the StdDev of a single frame is 5.6/sqrt(2) = 3.9e

Mark

[AstroScience]

Hi Mark,
I think I found my missing piece, thank you.
Manually I used Master bias for subtraction and script uses single bias frame, now everything matches.
Thank you.