Scientific Impact of the Operating Temperature for NFIRAOS on TMT

We present the scientific gain enjoyed by client instruments when NFIRAOS is cooled. If NFIRAOS is cooled to -24 ◦ C, the background contribution of NFIRAOS will not exceed 15% of the background from sky plus TMT (for a telescope build to current requirements on Mauna Kea). If cooled further to -30 ◦ C, the K-band inter-OH background-limited exposure times could decrease by more than 7%. We evaluate these gains achieved by cooling NFIRAOS in light of increased technical risks and costs.