<title>GOES-8 and -9 image navigation and registration operations</title>

Abstract

GOES 8/9 presents a new challenge to the National Environmental Satellite, Data, and Information Service's (NESDIS) Office of Satellite Operations. In the previous series of spin stabilized GOES satellites, the image navigation was performed off-line with little operator intervention or oversight. This system provided accuracy to 10 KM. However, the more stringent 4 KM navigation requirements of the new generation of three axis stabilized GOES satellites has resulted in a far more demanding image navigation and registration (INR) operation. The new system requires continuous observation gathering and monitoring of performance along with commanding real time corrections to the on-board image motion compensation system to maintain accuracy. All this must be accomplished while providing images as frequently as every 7.5 minutes in rapid scan mode and operating in the independent sounder. Once the GOES 8/9 navigation system was operational, it became apparent that there were several sources of pointing error which were not anticipated prior to launch. Most of these problems are related to special operational modes of the Earth sensor. It became necessary to devise new operational work-arounds for these problems to minimize the impact on the user community and continue to provide within specification INR performance. This paper will describe the GOES 8/9 INR operation and how it is integrate into the instrument and spacecraft command schedules. It will also describe the various operational solutions which NESDIS devised to overcome INR errors.