The dark maps used to correct for the dark current are affected by read noise and dark current noise. As a result, in the simple case of a single dark frame subtraction, both these noises have to be multiplied by $\sqrt2$. This will become a bit more complicated when multiple dark frames will be used to computed a dark map.
The dark maps used to correct for the dark current are affected by read noise and dark current noise. As a result, in the simple case of a single dark frame subtraction, both these noises have to be multiplied by $\sqrt2$. This will become a bit more complicated when multiple dark frames will be used to computed a dark map.