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5.1 Dewar Design and Maintenance

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