Once the set of science exposures and any additional target acquisition or calibration exposures required for the science program have been determined, they must be converted into a total number of orbits. Generally, this is a straightforward exercise involving tallying up the overheads on the individual exposures and on the selected pattern (see Chapter 11), packing the exposure and overhead times into individual orbits, and tallying up the results to determine the total orbit request. This process may need to be iterated, in order to seek the most efficient use of the orbit time.
We refer to the Call for Proposals/Phase I Proposal Instructions for information on the Observatory policies and practices with respect to orbit time requests and for the orbit determination. Below, we provide a summary of the NICMOS specific overheads, and give an example to illustrate how to calculate orbit requirements for Phase I Proposals.
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