NAME ORG. SIGNATURE DATE

Abstract

Small changes in the pointing direction of NGST will be required as part of target acquisition and dithering. Some portion of these changes may be accomplished by moving the entire observatory, other portions might be accomplished by moving a mirror. The purpose of this document is to outline the expected scientific drivers for different kinds of motions, estimate their scale and frequency, and assess their importance to the overall science goals of the observatory. Such information is an important input to deciding how efficient and accurate to make the small-angle maneuvers, and in deciding how they should be accomplished.