Moving Target Policies
Science requirements for moving targets, as well as brief descriptions and links to appropriate pages about policies that affect moving target observing programs, are presented in this article.
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Performance requirements and limitations for moving target observations
SR-31, Science Requirements Document, pg. 8-7 says: "When commanded, the Observatory shall compensate for the apparent motion of a moving target which exhibits an angular velocity between 0 and 75 mas/s with respect to a guide star that remains within a single Fine Guidance Sensor field of view." Note that this value was increased from 30 mas/s after commissioning).
Tracking capability at the above rates provides access to a large number of near-Earth asteroids (NEAs), Mars and all of the more distant planets and their moons, asteroids, KBOs, and most comets. Precise orbital elements (see, e.g. Moving Target Observing Strategies) are needed in order to place moving targets on specific NIRSpec slits, MIRI MRS, and NIRSpec IFU. There are no specific requirements on image quality for observations of moving targets, but on-orbit performance shows that it is very similar to that for fixed targets. Observation durations (and those exposure times) are limited by the length of time a guide star remains within the field of view of a Fine Guidance Sensor (see Moving Target Acquisition and Tracking).
Target of opportunity (ToO) policy
See also: JWST Target of Opportunity Observations
The proposer should be aware that only a small number (~3) of disruptive target of opportunity activations will be allowed during any particular cycle due to their effect on the schedule. See Target of Opportunity Observations for a more thorough description of the ToO policy for JWST.
Duplication policy
See also: JWST Duplicate Observations Policy, JWST Observation Duplication Checking
Observations of the same target with the same instrument and mode are considered duplicate observations. Duplicating an observation is typically discouraged unless the target shows intrinsic variability or a large-time baseline is needed to achieve the science goals.
See JWST Observation Duplication Checking for how to check for duplicate observations.
Moving target-specific overheads
See also: JWST Observing Overheads Summary
See the Moving Target Overheads article for a description of general overheads that apply to moving target observations.
References
Kelley, M.S.P., et al. 2016, PASP, 128, 018009 (arXiv)
Cometary science with the James Webb Space Telescope
James Webb Space Telescope Project, Science Requirements Document (July 10, 2012)