Scheduled outages
- Scheduled observation outages due to spacecraft events
- AHI's automatic sun avoidance function for the spring and autumn eclipse periods
Scheduled observation outages due to spacecraft events
The observation schedule of Himawari-8/9 AHI contains scheduled outages for the spacecraft events listed in following Table. Full-disk observation on the hour and on the half hour (i.e., at 00 and 30 minutes) is continued during these events, and regional observation is also performed.
| Event | Frequency | Time | Scheduled outage |
|---|---|---|---|
| North-south maneuver1 | Alternate Mondays2 | Not fixed (except every hour on the hour/half hour) |
One full-disk observation (Regional observation continued) |
| East-west maneuver1 | Alternate Thursdays and Fridays2 | ||
| Unloading3 | Twice a day | 02:50 and 14:50 UTC | |
| Solar calibration4 | Approx. once every two weeks |
20:40, 20:50 or 21:10 UTC |
1 For station maintenance
2 North-south and east-west maneuvers performed in the same week
3 Wheel momentum unloading for attitude control
4 Solar diffuser observation for reflective band calibration (bands 1 - 6)
AHI's automatic sun avoidance function for the spring and autumn eclipse periods
Around midnight during the spring and autumn eclipse periods, sunlight can enter the AHI sensor when the sun and the earth occasionally lie in an approximate line with the satellite. To avoid this, the AHI has a function by which part of the observation area can be automatically skipped based on prediction of the sun's position and potential problem areas.
This operation is performed not only in Full Disk observation but also in Japan Area and Target Area observation, resulting in images with some data missing. If the area to be skipped is expected to cover the whole domain of Target Area observation, observation will not be performed.