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Hubble Space Telescope
FOC Instrument Science Report 057

FOC Instrument Science Report 057 3/2/92

"The FOC Polarizing Filters"
by P.E. Hodge

Abstract excerpted from the report:

This report describes preliminary calibration of the FOC polarizing filters. 
The approximate position angles of the filters were determined to be as
follows. The POL0 filter passes light with electric vector parallel to the
sample direction. The POL60 polarization direction is 60 degrees counter-
clockwise from POL0, as projected onto the sky, and the POL120 polarization
direction is 120 degrees counterclockwise from POL0 as projected onto the
sky. These position angles should be correct to within 10 degrees, and
more accurate values will be obtained by further analysis of existing data.
Additional observations will be needed to measure the image shifts and the
relative throughputs of the polarizing filters.