Consider a target to be imaged with WFC in a given filter in one orbit. Using the Exposure Time Calculator
(ETC
), we find that we need 2400 seconds of exposure time to reach the desired level of signal-to-noise ratio. Given that the observation must be split into a series of two exposures by CR-SPLIT (CR-SPLIT=2), we map the overheads and the science exposure times onto the orbit as follows:
Thus, the two WFC exposures totaling 2400 seconds make full use of the typically available time in one orbit. The exposure times can be adjusted if the actual target visibility time differs from the derived total used time.
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