Group Scheduling Assumptions
JWST exposure groups with short duration will receive a warning or error based on the estimated minimum duration of the group.
Group links with short durations will receive a warning or error based on the estimated minimum duration of the group, which includes the durations of all of the component Observations’ visits and slews as well as a statistical overhead for required Observatory maintenance activities. Table 5, below, shows the overhead duration and period for these activities:
Table 1. Overheads for minimum group duration
Overhead | Duration(min) | Period(days) |
|---|---|---|
Wavefront Sensing | 46 | 2 |
Wavefront Control | 107 | 14 |
Momentum Unloads | 180 | 7 |
Station Keeping | 120 | 21 |
These overheads are used to compute the minimum group duration as follows:
- All visit durations, except the last(sequence) or shortest(group) visit are summed, as well as the estimated slews between those visits.
- Based upon that summed duration, for each of the overheads in table 5, add floor(summed duration/period) times the overhead duration.
If the requested link duration is less than the duration summed in step 1, an error will be generated. A warning will be generated if the duration is less than the value calculated in step 2.