Michelle Readnoise

For Michelle the readnoise from the calibration system is also first divided by a factor to take multiple non-destructive reads into account:

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

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.

The formula used to determine the variance due to readnoise is:

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

where RNE is the readnoise per exposure, in electrons, N_e is the number of exposures per integration, and gain is the detector gain in electrons per ADU.