Proc. SPIE 5901, 590118, 1−10, 2005
Solar Physics and Space Weather Instrumentation
S. Fineschi and R.A. Viereck (eds.)
© SPIE − The International Society for Optical Engineering

Space performance of the multistage labyrinthine SMEI baffle

A. Buffington, B.V. Jackson and P. Hick
Center for Astrophysics and Space Sciences, University of California San Diego


The Solar Mass Ejection Imager (SMEI) was launched on 6 January 2003, and shortly thereafter raised to a nearly circular orbit at 840 km. Three SMEI CCD cameras on the zenith-nadir oriented CORIOLIS spacecraft cover most of the sky beyond about 20° from the Sun, each 102-minute orbit. Data from this instrument provide precision visible-light photometric sky maps. Once starlight and other constant or slowly varying backgrounds are subtracted, the residue is mostly sunlight that has been Thomson-scattered from heliospheric electrons. These maps enable 3-dimensional tomographic reconstruction of heliospheric density and velocity. This analysis requires 0.1% photometry and background-light reduction below one S10 (the brightness equivalent of a 10th magnitude star per square degree). Thus 10-15 of surface-brightness reduction is required relative to the solar disk. The SMEI labyrinthine baffle provides roughly 10-10 of this reduction; the subsequent optics system provides the remainder. We analyze data obtained over two years in space, and evaluate the full systems stray-light rejection performance.