This directory contains the calibration data files for the coronal UV-EUV radiometer "LYRA" onboard the PROBA2 mission of the European Space Agency. These files include the spectral responses for each channel, as well as a file for each unit tracking its degradation. 

The LYRA instrument is composed of three redundant units, each constituted of four broadband channels. The spectral response of each channel is stored in a separate text file named "respABM_chxy.dat". Here, x is the unit number and can take the values 1 (calibration unit) , 2 (nominal unit), or 3 (back-up unit). y is the channel number and can take the values 1 (Lyman-alpha channel), 2 (Herzberg channel), 3 (Aluminum channel), or 4 (Zirconium chanel). Each of these files is composed of three columns: the wavelength (in nm), the spectral response (in A/W), and its uncertainty (in A/W).

The degradation files for units 1, 2, and 3 are respectively named "degrad_unit1.txt", "degrad.txt", and "degrad_unit3.txt". Each contains 5 columns, of which the first column is the day from the beginning of the mission, and the next four columns are signal references in DN/ms for the four LYRA channels. These references are fitted from observed values, that were corrected for dark currents, distance from the Sun, and solar activity (using the data of channel 14 as a proxy).