Astronomical measurements of the brightness, color, and polarization of light from solar system bodies at phases not visible from Earth are planned for Pioneers F and G. An imaging photopolarimeter (IPP) in the scientific payloads will make these measurements and produce line-scan color images of Jupiter. The IPP collects light with a 2.5 cm aperture telescope that is able to turn in the plane containing the spin axis. Data are taken in scans around the spin axis along a cone whose apex angle

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... periodically changed by stepping the telescope. The light is analyzed for polarization, divided into blue and red components, and detected by four photomultipliers having electron channel multipliers. Appendix A gives a summary of instrument characteristics.