Tab. 2.

Type of calibration measures performed for the experimental protocol with corresponding calibration devices and application frequencies

Calibration Type	Calibration device (references)	Frequency
Wavelength calibration of the spectrograph	HgAr Lamp (LSP035 HgAr Line Source, LOT)	monthly
Intensity response calibration	Calibrated Tungsten Lamp (DH-2000, Mikropack)	monthly
Background substraction	Shuttered light source	every 2 hours
Diffuse reflectance standard measurement	Integrating Sphere (ISP-30-6-IRRAD, Mikropack)	daily
Illumination energy normalization	Power meter (841-PE + 818-UV, Newport)	daily