Your numbers
Sky background given as
Electrons per pixel per second
A test sub’s background level (ADU)
Camera read noise (e-)
From the maker’s data at the gain you use.
Sky background (e-/pixel/s)
Robin Glover’s formula needs it in these units.
Background level in a test sub (ADU)
Median of an empty patch of sky.
Bias offset (ADU)
The level of a zero-length frame. Empty means 0.
Gain (e- per ADU)
Test sub length (s)
Constant C
About 10 for 10% extra noise, about 20 for 5%.
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