Administrative, NOAA-18 Reduced Gyro Enhanced Flight Software On-Orbit Test on 19 October 2011 - Issued: 5 October 2011 1400 UTC

Topic: NOAA-18 Reduced Gyro Enhanced Flight Software On-Orbit Test

Date/Time(UTC) Message Issued: October 5, 2011, 1400 UTC

Product(s) Involved/Affected: All data and products from NOAA-18 (AVHRR, AMSU-A, HIRS, MHS, & SBUV)

Date/Time(UTC) of Initial Implementation: October 19, 2011, Time 12:31 UTC

Date/Time(UTC) of Expected End: October 19, 2011, Time 20:52 UTC

Length of Outage: 8.5 hours

Details/Specifics of Change: From 19 October 2011 at 12:31 UTC (orbit 33046) to 19 October 2011 at 17:32 UTC (orbit 33049), NOAA-18 will be placed into the ACS Reduced Gyro Mode for a flight software test of the enhanced Reduced Gyro software with the degraded laser gyro correction for about 5 hours (3 orbits). Products may be impacted by larger than normal yaw attitude disturbances. The performance of NOAA-18 instrument L1b data is expected to be similar to the counterpart of NOAA-15, which has been operated in the enhanced Reduced Gyro Mode since March 17, 2010. The geolocation errors could be up to 15 km.

Upon exiting the test on October 19th on REV 33049 AOS 17:32 UTC the spacecraft will be reconfigured for normal operation (all three gyros available for ACS control). The spacecraft will be commanded back to nominal mode (all three gyros and sun sensor available for ACS control) on REV 33051 at 20:52 UTC. This is 2 orbits after the end of the Reduced Gyro Mode enhanced flight software test with the bad MIMU.

Backup date due to a Critical Weather Day Period cancellation is 02 November 2011 roughly in the same UTC times as above.

Products that use NOAA-18 that will be affected:
ATOVS Polar Soundings
Radiation Budget
Fire Identification Mapping and Monitoring Algorithm (FIMMA) for Hazard Mapping system (HMS) input
SST and Coastwatch
Microwave Surface and Precipitation Products (MSPPS)
Microwave Integrated Retrieval System (MIRS)
Blended TPW
Ozone: SBUV/2
Ozone: TOAST
Ensemble Tropical Rainfall Potential (eTRaP)
Global Vegetation Index Products (GVI)

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ESPC Operations at at 301-817-3880
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Dejiang Han at at 301-817-4119

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