A system to reduce jitter for the GOES-N/O/P solar X-ray imager

Abstract

A jitter compensation system is incorporated in the Solar X-ray Imager (SXI) that will be mounted to the solar array wing of the GOES N spacecraft, the next in the series of NOAA weather satellites. The SXI obtains images in a back-thinned CCD with 5 arcsec pixels. The SXI incorporates a pointing aspect sensor manufactured by the Adcole Corporation that is used in a semi-closed loop system with the SXI flight computer to shift the detected image during an exposure along the readout columns of the CCD in order to compensate for jitter in one dimension. Simulations of the predicted motions caused by the GOES spacecraft and self-induced by the SXI filter wheels indicate that the jitter as experienced by the SXI instrument will be primarily along one axis, parallel to the east-west direction, with amplitudes in the tens of arcseconds and with dominant frequencies less than approximately 10 Hz. The SXI CCD columns are aligned along this direction in order to make possible on-chip compensation. The SXI motion compensation system has been evaluated with realistic models for the expected spacecraft jitter and assuming a performance algorithm for the SXI instrument. Our analysis indicates that the X-ray spatial imaging performance will be improved when the jitter compensation system is used. We discuss the design and analysis predictions.