reaching the sensor (Qcal) normalised for solar irradiance using ratio
of spectral radiance scaling factors LMAXl and LMINl (range 0e1;
NASA, 2011) over the maximum and minimum energy (Qcal max/Qcal
min) measured in each band pixel (values of DN range from 1 to 255
for 8 unsigned Level-1 Product Generation System products).