The effectiveness of the proportional counter as a solar X-ray monitor on the NEAR mission

A proportional counter with a special mask/filter (SMPC) designed to measure solar output from 1 to 10 keV and to enhance sensitivity at higher energies where the solar flux is lower, as well as an experimental Si PIN detector (SMPN) are being used to measure solar flux on the Near Earth Asteroid Rendezvous (NEAR) mission. The complimentary nature of their performances is considered.