|COS Instrument Handbook for Cycle 25|
To increase observing efficiency, a special feature of the COS instrument commanding allows a portion of the instrumental overheads for the first exposure of a visit to be performed during the initial guide-star acquisition. These will usually be target-acquisition exposures. As a result, up to 340 s of instrumental overheads (Table 9.3, Table 9.4, and Table 9.5), but not observatory or acquisition overheads (Table 9.2 and Section 9.4), may be hidden in this fashion. See Section 9.7 for examples.