In the real-time processing, only the receiver gain and bandpass, the atmospheric transmission and the radiometric correction have been calibrated.
Fitting of the temporal variations of the global antenna gain (the so-called amplitude calibration) is performed in CLIC by fitting splines functions with time steps of 3-6 hours (SOLVE AMPLITUDE [/WEIGHT] [/POL degree] [/BREAK time]) and can be done either in baseline-based or in antenna-based mode. Note that in the latter case, the averaged amplitude closures are computed, as well as their standard deviations. The amplitude closures should be close to 100%. Strong deviations of amplitude closures from 100% are an indication of amplitude loss on long baselines, due to phase decorrelation during the time averaging. The fit then shows systematic errors; if this occurs, baseline based calibration of the amplitudes might be preferred.
The amplitude calibration involves interpolating the time variations of the antenna gains measured with the amplitude calibrator, assuming the its flux is known. The fitted splines must be as smoothed as possible in order to minimize the errors introduced on the source which is observed in between calibrators.