α factors as a function of time for all satellites calibrated by Sandanger et al. (2015), both detectors. Upper row, left to right: P1 and P2 energy channels. Middle row, left to right: P3 and P4 energy channels. Bottom row: P5 energy channel. α is found as a function of the cumulative integral flux with E > 90 keV for all energy channels. The standard deviations of α are plotted as vertical lines.