|COS Instrument Handbook for Cycle 26|
The first time that you acquire an object, you must include a 6-minute overhead for the HST guide-star acquisition. In all subsequent orbits of the same visit, you must include the 4-minute overhead for the guide-star reacquisition. If you are observing an object in the Continuous Viewing Zone (CVZ), then no guide-star re-aquisitions are required.You must allocate additional time for each deliberate movement of the telescope; e.g., if you are performing a target-acquisition exposure on a nearby object and then offsetting to your target, or if you are taking a series of exposures in which you move the target on the detector (POS-TARG), then you must allow time for telescope motion. The time varies depending on size of the slew; see Table 9.2.Table 9.2: Generic Observatory Overhead Times.
10 arcsec < Offset < 1.5 arcmin1 1.25 arcsec ≤ Offset ≤ 10 arcsec