Topic: NOAA-21 VIIRS Lunar Calibration Roll Maneuver Scheduled for April 27, 2026

Date/Time Issued: April 22, 2026 1437Z

Product(s) or Data Impacted: All NOAA-21 Sensor Data

Date/Time of Initial Impact: April 27, 2026 03:25:27Z

Date/Time of Expected End: April 27, 2026 03:38:32Z

Length of Outage: See Details.

Details/Specifics: On April 27, 2026, NOAA-21 will perform a spacecraft attitude maneuver for the VIIRS Lunar Calibration. Science data may be impacted while the spacecraft is pointing off-nadir during the attitude maneuver and the CERES instrument will not provide nominal science data as it will be placed in a contamination safe mode. The timeline of events for this maneuver are provided below.

The following observatory systems will be affected on April 27, 2026 during the Lunar Roll Activity:

03:25:58z - 03:38:00z HRD will be off, data for direct broadcast users will be unavailable

03:25:28z - 03:38:31z VIIRS encoder offset and gain will be set for Moon observation

03:26:00z - 03:38:00z NOAA-21 will be pointing off-nadir, collected data may be impacted and not disseminated.

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