Simulating ACQ/PEAK target acquisitions with the HST/FOS

A common target acquisition strategy with the Faint Object Spectrograph (FOS) on board the Hubble Space Telescope (HST) is to use a sequence of so-called ACQ/PEAK stages. Standard sequences and exposure times are given in the FOS Instrument Handbook (Keyes et al.~1995). The success of a given strategy is difficult to predict a priori for targets other than point sources. This paper describes software that simulates ACQ/PEAK acquisitions in a Monte-Carlo manner, for a variety of targets. The software is available from the FOS Instrument Scientists or from the author. It allows a proper quantitative assessment to be made of whether an acquisition will succeed, what exposure times should be used, and how the efficiency can be optimized.