Ok, figure 27, directly above that image, in the same paper, shows 3 calibrations.
And if you feel like there is almost enough information to work out what is happening, but some piece seems to be missing to make sense of the data and plots... too bad. Ask for help and you may get arguments and off topic nonsense, or maybe just crickets chirping in the background, but not what you are looking for. Good luck in your search.