change extreme values?

[ianan]

Change what happens to extreme values/ratios - make it more similar to how done in sswidl code?
https://hesperia.gsfc.nasa.gov/ssw/gen/idl/synoptic/goes/goes_tem_calc.pro
https://hesperia.gsfc.nasa.gov/ssw/gen/idl/synoptic/goes/goes_chianti_tem.pro