Spacecraft pointing control criteria for high resolution spectroscopy

A new pointing control criterion is derived to support high resolution space spectroscopy. The criterion maps desired specifications on allowable flux offset (imposed by scientists for accurate calculation of spectral line ratios) into standard pointing control definitions in terms of bias and jitter. In contrast to previous derivations, the new criterion is exposure dependent, and fully captures the beneficial smoothing effect of longer spectroscopy exposures on reducing flux offset. The criterion is easily visualized and allows a complete characterization of the allowable design space.