Two procedures dealing with distance estimation in space are analyzed. In one, formulae relating angular subtense to target distance are derived for spherical and disk objects. A design for a simple reticle to be used in distance estimation is described. In the other procedure, the utilization of illuminance from spherical and disk-shaped satellites for the purpose of relating it to object distance is examined. Formulae describing the relationships for certain cases are developed. The appearance of spherical satellites when illuminated by sources of both small and large angular subtense is dealt with in some detail.
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