The MUPUS calibration is described in the User Manual 
"RO-LMU-SW-V74 Version 2.1" Chapter 10 located in the Documents directory.
Calibration constants are provided in the files 
"PEN_Calib_Coefficients.txt" and "TM_Calib_Coefficients.txt" 
in the Calib directory.
The Calib directory further contains the file "Tau_FM.txt" which provides
the 4 filter transmission curves and infrared absorber emittance as 
a function of wavelength. 
This auxiliary data is required to derive brightness temperatures from digital
values.