Solar System Observations
JWST can observe most targets within our Solar System, although there are a few exceptions. The Sun, Earth, Mercury, Venus, and the Moon cannot be observed due to the orientation of JWST's sunshade. As moving targets, solar system targets may have reduced periods of visibility as compared to fixed targets. In Cycle 1 for moving targets, the rate of motion may not exceed 30 milliarcseconds per second. Proposers should consult the JDox Moving Target Field of Regard, JWST Moving Target Observations and the JWST Moving Target Visibility Tool pages for additional information in planning this type of observation.
NIRSpec MSA-based observations of moving targets may only be proposed using the MOS Longslit observing method with the Wide Aperture Target Acquisition or Verify Only TA options. MSA-based Target Acquisition (MSATA) is not possible on moving targets. Proposers must ensure that an ephemeris of sufficient accuracy is available for the appropriate epoch; observations that prove infeasible for technical reasons will be disallowed.