... Also the measured signals are affected by detector transients, altering the final results considerably. We present the design and the main features of a software package, developed in order to support the absolute calibration of the instrument. ... In case the fit is not successful, the average of the last 30% of the data is taken as the final signal. ... The two different symbols represent individual calibrations of the final background signals, using the first or the second FCS-signal. ...