ISAAC Readnoise

ISAAC uses the same formulae for calculating the readnoise variance as Michelle i.e.

$$RNE = \frac{RN}{\sqrt{\frac{N_{ND} * ( N_{ND} + 1 )}{12 * ( N_{ND} + 1 )}}}$$

and

$$V_{RN} = \frac{RNE^{2}}{N_e * gain^{2}}$$

where RNE is the readnoise per exposure, in electrons, RN is the readnoise in electrons, and N_ND is the number of non-destructive reads, N_e is the number of exposures per integration, and gain is the detector gain in electrons per ADU.