Advanced Geosynchronous Studies Imager: scanning CCD star detection

摘要

The AGSI design permits scan rates slow enough to detect stars as dim as visual magnitude eight in the coarse of normal imaging. This gives many times the number of stars seen with the current Geosynchronous Operational Environmental Satellite (GOES) Imager and can eliminate the need to schedule special star looks. Besides improving image navigation and registration accuracy, the frequency observations enable the Imager to fly aboard a spacecraft with loose attitude control. The slow scan rate is thanks to the long CCD detector arrays and to the time delay integration made possible by the unique windshield wiper scan pattern. The Bremer star detection algorithm describe can be implemented onboard to reduce downlink requirements and so permit star detection across a dedicated full silicon passband. The wide passband increases the number of detectable stars, and cross checking with narrower science passbands eliminates false alarms from high energy particles while preserving low detection thresholds and sensitivity.