The CCDs are mounted in KPNO universal dewars. The design of these dewars is such that they can be used in any position (up, down, or side-looking). On the echelle spectrograph, the dewar is used in a side-looking position. Approximate LN2 hold time is 12 hours, but in some telescope orientations a portion of the LN2 may spill out causing an earlier warming of the dewar. The dewar temperature shown on the telescope control panel or given by the command